GeneticsofStay-GreenTraitandItsAssociationwithLeafSpot ...NIELLI;themoderatelystay-greengenotypeswereICGV-IS 13015, ICGV-IS 13018, ICGV-IS 13041, ICGV-IS 13045, ICGV-IS13052,ICGV-IS13071,ICGV-IS13078,ICGV-IS

Research ArticleGenetics of Stay-Green Trait and Its Association with Leaf SpotTolerance and Pod Yield in Groundnut

Rukiya Danful1 Yussif Baba Kassim 1 Doris Kanvenaa Puozaa 2

Richard Oteng-Frimpong 2 Masawudu Abdul Rasheed2 Alexander Wireko-Kena1

and Richard Akromah1

1Department of Crop and Soil Sciences Kwame Nkrumah University of Science Technology Kumasi Ghana2Council for Scientific and Industrial Research-Savanna Agricultural Research Institute (CSIR-SARI) Tamale Ghana

Correspondence should be addressed to Doris Kanvenaa Puozaa doriskanpgmailcom

Received 31 January 2019 Revised 9 June 2019 Accepted 13 July 2019 Published 30 July 2019

Academic Editor Alpha Y Kamara

Copyright copy 2019 Rukiya Danful et alis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Despite its importance in providing income and food for smallholder farmers fodder for livestock and improving soil fertilitythrough biological nitrogen fixation groundnut yields are lowest on farmersrsquo fields in Sub-Saharan Africa due to biotic and abioticconstraints Foliar fungal diseases account for over 80 reduction in groundnut productivity in some parts of Ghana Un-fortunately chemical control of these foliar diseases has not yielded the desired results Meanwhile advances in phenotyping fordisease tolerance in other crops have established a strong relationship between stay-green trait and foliar disease toleranceHowever this relationship has not been explored in groundnut is study was designed to determine the genetic control of thestay-green trait and its relationship with leaf spot disease severity in groundnut Twenty-five advanced groundnut breeding lineswith varying degrees of tolerance for leaf spot tolerance were evaluated under diseased and disease-free conditions after whichfour were selected for genetic studies Results showed significant (plt 0001) differences among the genotypes for early leaf spot(ELS) late leaf spot (LLS) leaf area under greenness (LAUG) SPAD chlorophyll meter readings (SCMR) and yield traits Leafspot diseases caused 495 tmiddothaminus1 (6454) pod yield reduction in CHINESE the widely cultivated groundnut variety in Ghanaere was a strong correlation between LAUG and ELS (r 082 plt 0001) and LLS (r 063 plt 0001) and genotypes that werestay-green had tolerance to both diseases Stay-green trait in groundnut was detected to be under the control of a single recessivegene and hence may be used to select for ELS and LLS resistance

1 Introduction

Groundnut (Arachis hypogaea L) is an important legumi-nous crop that provides income and food for the poorsmallholder farmers in developing countries [1] e haulmsafter harvesting the pods are also used as nutritious fodderfor livestock especially during the dry season [2] As a resultgroundnut cultivation contributes to the sustainability ofcrop-livestock production systems in most African countriesincluding Ghana Although there has been a 92 expansionin the area under cultivation of groundnut since 2008 andthe release of high-yielding cultivars [3] Sub-Saharan (SSA)Africa contributes only about 24 to the total globalgroundnut production [1]

Biotic and abiotic stresses have caused yield stagnation ofgroundnut in SSA affecting its total production [2] Foliarfungal diseases are the major factors limiting groundnutproductivity [4] with Cercospora leaf spot (CLS) beingpredominant [5] In northern Ghana CLS has been shownto cause up to 812 reduction in pod yield in groundnut [6]e leaf spot diseases damage groundnut plants by reducingthe available photosynthetic area through reduction of leafarea index lesion formation and stimulating leaflet ab-scission [7 8] As a result it disrupts photosynthetic processwhich causes groundnut to produce less pods with inferiorquality e infections mainly attack the leaves leading topremature defoliation hence causing increase in stem per-centage of the resulting fodder which reduces in vitro

HindawiInternational Journal of AgronomyVolume 2019 Article ID 3064026 11 pageshttpsdoiorg10115520193064026

digestibility [9] when the haulms are fed to animals Leafspot disease occurs in two forms early leaf spot (ELS) whichis caused by Cercospora arachidicola S Hori (Berk andM ACurtis) and late leaf spot (LLS) caused by CercosporidiumpersonatumDeighton [10] Early leaf spot is characterized bylight brown spots surrounded by yellow halo while spots oflate leaf spot are black and usually without yellow halo [11]ELS and LLS typically occur together and their spread andseverity are influenced by the field cropping history tem-perature and relative humidity [12] e leaf spot diseaseepidemics are affected by weather patterns such as hot andwet conditions [13] Temperatures in the range of 25 to 30degCand high relative humidity favour infection and diseasedevelopment [14]

Efforts have been directed at chemical control of leaf spotdiseases in northern Ghana [6] However it has only beenpartially effective in controlling the disease on farmersrsquo fields[8] and substantially increases cost of production e de-velopment and adoption of leaf spot resistant cultivars willtherefore be a breakthrough to resource poor farmers in themiddle- and low-income countries [15] including Ghanawho cannot afford chemical control measures

Genetic variation exists in cultivated groundnut for bothELS and LLS resistance but the resistant genotypes aregenerally late maturing [16] Direct selection for leaf spotresistance in groundnut is also difficult and has been re-ported to be associated with low yield poor pod and kernelcharacteristics and late maturity [16] As a result there is theneed to consider other physiological traits that can confertolerance to the two foliar diseases and enhance pod andhaulm yields

Stay-green is an important trait that allows plants toretain their leaves in an active photosynthetic state whenexposed to stress conditions [17] It has been found to bepresent in different crops [17] and widely used in breedingfor disease resistance [18] e stay-green trait can be scoredon a large number of entries [19] and is associated with otherimportant agronomic and physiological traits It enablesplants to maintain active photosynthesis under drought [20]enhances higher nitrogen concentration in plant organs [21]confers tolerance to drought heat cold pathogens andresistance to lodging [22 23] and performs better under lownitrogen conditions [24] Maintenance of green leaf areathrough grain filling has been associated with increasedgrain yield in wheat [25 26] maize [27] and sorghum [28]e stay-green trait occurs at three levels in plants namelythe cell leaf and whole plant levels [29] However green leafarea at physiological maturity has proven to be a goodmeasure of stay-green [30 31] with the potential of en-hancing foliar disease resistance in groundnuts

e objectives of this study were to determine the (i)genetic control of the stay-green trait in groundnut and (ii)association between stay-green trait and leaf spots severity ingroundnut

2 Materials and Methods

21 Site Plant Materials and Design of Experiment eexperiment was carried out at the research station of Council

for Scientific and Industrial Research-Savanna AgriculturalResearch Institute (CSIR-SARI) Tamale Ghana located at09deg 25prime 41Prime N 00deg 58prime 42PrimeW and altitude of 183m above sealevel e study area is characterized by a relatively dryclimate with a unimodal rainfall ranging between 900 and1200mm annually e rainy season begins in May and endsin October with few scattered precipitation in Novembere soils of the area are Ferric Luvisols of the Tingoli series[32 33]

A total of 25 advanced breeding lines of groundnut withvaried levels of tolerance to leaf spot diseases were selectedfrom the germplasm collection at the CSIR-SARI (Table 1)ese lines comprised of four (4) released varieties andtwenty-one (21) advanced breeding lines assembled fromICRISAT EIR in Mali and INERA in Burkina Faso

e study comprised of two parts (i) evaluation of thegenotypes for the stay-green trait and leaf spot (ELS andLLS) severity and (ii) genetic analysis of the selected ge-notypes for stay-green trait

22 Evaluation of the Genotypes for the Stay-Green Trait andTolerance to Leaf Spot Diseases Evaluation of the 25 geno-types for leaf spot disease tolerance was done in the majorcropping season when the disease incidence is usuallyhighest Disease infection was done under natural conditionswith spreaders planted at border and between rows to ensureinoculum pressure for the disease development in 2016 Toensure zero incidence of the leaf spot diseases the genotypeswere evaluated for the stay-green trait in the minor season of2016

e experiment was laid in a partial lattice design withfive blocks replicated three times A plot comprised of fourrows of 4m long with inter- and intrarow spacing of 05mand 01m respectively One seed was planted per hill fol-lowing the procedure of Naab et al [7 8] e genotypeswere grouped into late medium and early maturing basedon the length of their maturity periods Hence plantingdates were staggered in the order of late medium and earlymaturing group respectively to ensure that their re-productive stages (stage of high disease infection) coincidedTriple superphosphate (TSP) was applied at a rate of 60 kgP2O5 haminus1 at two weeks after plantinge experiments werefurther supplemented with grounded oyster shells at a rate of200 kgmiddothaminus1 to supply calcium [34]

23 Genetic Analysis of the Stay-Green Trait in GroundnutAfter the field evaluation two groundnut genotypesexpressing the stay-green trait and resistance to leaf spotdiseases (NKATIESARI and ICG 7878) were selected andcrossed with two other genotypes CHINESE and ICGV-IS13081 that were non-stay-green and susceptible to leaf spotdiseases using a biparental mating design e F1 progenyfrom each cross divided into two sets one set was advancedto F2 whereas the other set was saved for field evaluation

e parents F1 and F2 were evaluated for leaf spotseverity and the stay-green trait during the major and minorseasons respectively in 2017 Spreaders were used to en-hance the disease inoculum pressure on the disease

2 International Journal of Agronomy

evaluation plots e experiment was arranged in a ran-domized complete block design (RCBD) with three repli-cations Single row plots of 2m length were used with inter-and intrarow spacing kept at 05m and 01m respectively

24 Data Collection Starting from pod initiation to phys-iological maturity visual scoring for severity of ELS and LLSinfection and stay-green were carried out at two weeksintervals e severity of ELS and LLS infection was scoredon a scale of 1 to 9 with 1 being completely resistant and 9 adead plant [11]e severity scores were used to compute thearea under disease progress curve (AUDPC) value [35] estay-green characteristic of the genotypes was scored on ascale of 1 to 5 based on the proportion of the total leaf areathat had senesced with 1 being no leaf senescence and 5completely senesced plant [36] e stay-green scores wereused to compute the leaf area under greenness (LAUG)values [18] Lower values of AUDPC and LAUG representhigher disease tolerance (lower disease severity) and stay-green in groundnut respectively

At pod initiation data were also collected on leafchlorophyll (SCMR) using a chlorophyll meter (TYS-A) andnumber of green leaves and leaf area (LA cm2) using a leafarea meter (YMJ-B) In measuring SCMR second fullyopened leaves were clipped with the chlorophyll meter untilreadings stabilized and recordede leaves used to measurethe SCMR were plucked for immediate leaf area measure-ment in the lab Pod yield (PY tmiddothaminus1) and reduction in podyield (RPY tmiddothaminus1) due to disease were also recorded at

maturity All data were taken on five (5) randomly selectedplants

AUDPC LAUG and RPY were computed using theformulae below

AUDPC 1113944a

i1

Yi + Y(i+1)

21113896 1113897x t(i+1) minus ti1113872 11138731113890 1113891

LAUG 1113944a

i1

Si + S(i+1)

21113896 1113897x t(i+1) minus ti1113872 11138731113890 1113891

RPY PYdfp minusPYdp

(1)

where Yi is the disease level at time ti t(i+1)minus ti is the time indays between two sequential diseasestay-green scores Si isthe visual score at time ti PYdfp is the pod yield on disease-free plot and PYdp is the pod yield on disease plot

25 Data Analysis Statistical analysis was done using the Rstatistical software version 351 [37] Using the lme4package [38] a linear mixed effect model was fitted by therestricted maximum likelihood (REML) procedure to de-termine genotypic effects using the equation below

Yijk μ + rk + bjk + gi + εijk (2)

where Yijk μ rk bjk gi and εijk denote the observation ongenotype i in block j of replication k grand mean effect ofreplication k effect of block j nested within replication keffect of genotype i and the residual effect respectively

Table 1 Genotypes used in the study and their characteristics and sources where they were obtained

Genotypes Attributes SourceNKATIESARI Medium maturity resistant to ELS and LLS SARI GhanaYENYAWOSO Early maturity ELS and LLS susceptible SARI GhanaKPANIELLI Late maturity ELS and LLS resistance SARI GhanaCHINESE Early maturity susceptible to ELS and LLS SARI GhanaGK 7 Late maturity ELS and LLS resistance IER-Burkina FasoGAF 1665 Late maturity ELS and LLS resistance SARI GhanaGAF 1723 Late maturity ELS and LLS resistance SARI GhanaSUMNUT 23 Medium maturity ELS and LLS tolerance NigeriaICGV 00064 Late maturity ELS and LLS resistance ICRISAT MaliICGV-IS 08837 Medium maturity ELS and LLS tolerance ICRISAT MaliICGV-IS 13015 Medium maturity foliar disease tolerance ICRISAT MaliICGV-IS 13018 Medium maturity foliar disease tolerance ICRISAT MaliICGV-IS 13041 Medium maturity foliar disease tolerance ICRISAT MaliICGV-IS 13045 Medium maturity foliar disease tolerance ICRISAT MaliICGV-IS 13052 Medium maturity foliar disease tolerance ICRISAT MaliICGV-IS 13071 Medium maturity foliar disease tolerance ICRISAT MaliICGV-IS 13078 Medium maturity foliar disease tolerance ICRISAT MaliICGV-IS 13079 Medium maturity foliar disease tolerance ICRISAT MaliICGV-IS 13081 Medium maturity foliar disease tolerance ICRISAT MaliICGV-IS 13086 Medium maturity foliar disease tolerance ICRISAT MaliICGV-IS 13110 Medium maturity foliar disease tolerance ICRISAT MaliICGV-IS 13113 Medium maturity foliar disease tolerance ICRISAT MaliICGV-IS 13114 Medium maturity foliar disease tolerance ICRISAT MaliICGV-IS 13998 Medium maturity foliar disease tolerance ICRISAT MaliICG 7878 Late maturity ELS and LLS resistance ICRISAT MaliELS early leaf spot LLS late leaf spot

International Journal of Agronomy 3

Replicates blocks nested within replicates and theresidual effect were all considered as random effects andgenotypes as fixed effect Fixed effect estimates werecompared using t-tests based on Satterthwaitersquos methodfor correcting degrees of freedom for Levenersquos test ofhomogeneity of variance [39] Effect comparison wasdone using the lmerTest package [40] CHINESE which isthe most cultivated groundnut variety in Ghanarsquos guineasavanna agroecology was set as the intercept using theldquorelevel()rdquo command of R

Based on the scale used in scoring stay-greenness if agenotype has LAUG score of between 1 and 28 it wasregarded as stay-green between 29 and 42 as moderatelystay-green while between 43 and 70 as non-stay-green[36] e genotypes were assigned to the various stay-green classes (stay-green moderately stay-green andnon-stay-green) using the LAUG scores e differentclasses were compared using variance component analysisand the comparison was done with the agricolae package[41] of R To confirm the influence of stay-greenness onleaf spot tolerance principal component analysis (PCA)was computed for the AUDPC scores of ELS and LLSusing the vegan package [42] of the R statistical software

Coefficients of relationship between pod yield LAUGSCMR LA ELS and LLS AUDPC were estimated basedon Pearsonrsquos correlation criteria while boxplot analysiswas used to plot mean leaf chlorophyll content of thegenotypes against growth stage to understand the varia-tion of progress of leaf chlorophyll degradation amonggenotypes till the reproductive stage

For the genetic analysis the chi-square test was used todetermine if the ratios of segregations observed at F2 fittedexpected Mendelian ratios Broad and narrow senseheritability were estimated using the variances from bi-parental mating design (BIP) of parents and offsprings[43] (Table 2)

δ2b 12VA +

14VD + VEC

1rMS1 minus MS2( 1113857

δ2w 12VA +

34VD + VEW MS2

(3)

Narrow and broad sense heritabilities were estimated asshown in the following equations [44]

covariance of offspringmidparent value

12VA

h2

VA

VA + VD + VEW

H2

VD

VA + VD + VEW

(4)

where h2 is the narrow sense heritability H2 is the broadsense heritability VA is the additive variance VD is thedominance variance VEC is the environmental varianceamong families and VEW is the environmental variancewithin families

3 Results

31 Variation of Area under Disease Progress Curve for LeafSpots and Leaf Area under Greenness among GroundnutGenotypes e genotypes evaluated differed significantly(plt 0001) for leaf spot disease incidence and severity(Table 3) CHINESE had the highest AUDPC for ELS butthe severity was similar to that of ICGV-IS 13081 ICGV-IS08837 ICGV-IS 13113 ICGV-IS 13114 ICGV-IS 13110ICGV-IS 13018 ICGV-IS 13078 ICGV-IS 13041 andSUMNUT 23 while NKATIESARI expressed the lowestAUDPC for ELS (Table 3)

SUMNUT 23 had the highest AUDPC for LLS but wassimilar (pge 005) to that of CHINESE (Table 3) e score ofCHINESE however did not differ statistically for LLS fromthat of ICGV-IS 13113 ICGV-IS 13110 ICGV-IS 08837ICGV-IS 13041 ICGV-IS 13114 ICGV-IS 13018 and ICGV-IS 13081 e least AUDPC for LLS was expressed by ICG7878 and GAF 1665

Furthermore CHINESE had the highest leaf area undergreenness (LAUG) (5854 plt 0001) followed by ICGV-IS08837 while NKATIESARI had the lowest LAUG (Table 3)Among the 25 genotypes tested nine were categorized asstay-green 12 moderately stay-green and only four as non-stay-green (Table 3) e stay-green genotypes consisted ofNKATIESARI ICG 7878 GAF 1665 GAF 1723 GK 7ICGV 00064 ICGV-IS 13114 ICGV-IS 13998 and KPA-NIELLI the moderately stay-green genotypes were ICGV-IS13015 ICGV-IS 13018 ICGV-IS 13041 ICGV-IS 13045ICGV-IS 13052 ICGV-IS 13071 ICGV-IS 13078 ICGV-IS13079 ICGV-IS 13086 ICGV-IS 13110 ICGV-IS 13113 andYENYAWOSO while CHINESE ICGV-IS 13081 ICGV-IS08837 and SUMNUT 23 were considered as non-stay-green(Table 3)

32 Chlorophyll Content Leaf Area (LA) Leaf Number PodYield andReduction inPodYielddue toDisease ofGroundnutLeaf chlorophyll content measured on genotypes underdisease-free conditions at pod initiation and midpod fillingwas highest (plt 001) in NKATIESARI and GAF 1665compared to CHINESE (Table 4) CHINESE had lower leafchlorophyll than GAF 1723 KPANIELLI NKATIESARIand SUMNUT 23 at pod initiation while KPANIELLINKATIESARI and SUMNUT 23 had lower leaf chlorophyllcontent at midpod filling (Table 4) At physiological ma-turity GK 7 had significantly (plt 005) higher leaf chlo-rophyll content while ICGV-IS 08837 had lower leafchlorophyll than CHINESE respectively

Table 2 Variance components for biparental mating design

Sources of variation df Ms EMSBetween families (12n)minus 1 MS1 δ2w + rδ2bWithin families (12n)(rminus 1) MS2 δ2wTotal (12n)minus 1 mdash mdashn number of parents sampled per cross r number of individuals sampledper cross δ2b between family variance δ2w within family variance MS1between family mean square MS2 within family mean square


Under disease conditions GK 7 had the highest leafchlorophyll content at pod initiation which was significantly(ple 001) different from that of CHINESE (Table 5) Also GAF1665 GAF 1723 and SUMNUT 23 all had higher leaf chlo-rophyll than CHINESE At midpod filling all the genotypeswere similar in terms leaf chlorophyll content except ICGV-IS13052 which had significantly (plt 005) lower chlorophyllcontent than that of CHINESE (Table 5) At physiologicalmaturity NKATIESARI had the highest leaf chlorophyll con-tent under disease conditions which was significantly (ple 001)different from that of CHINESE GAF 1665 GK 7 ICG 7878ICGV-IS 13015 ICGV-IS 13113 andKPANIELI had higher leafchlorophyll content than that of CHINESE (Table 5)

e total number of green leaves per plant varied(plt 001) among the genotypes GAF 1665 GAF 1723 GK7 ICG 7878 ICGV-IS 00064 KPANIELI and NKATIESARIhad significantly (plt 001le 0001) higher number of greenleaves than CHINESE at pod initiation (Table S1) Atphysiological maturity CHINESE had similar number ofgreen leaves compared to most genotypes However ICG7878 NKATIESARI KPANIELI ICGV-IS 13114 ICGV-IS13045 ICGV-IS 13015 ICGV-IS 00064 GAF 1665 GAF1723 and GK 7 had significantly (plt 005le 0001) highernumber of green leaves

Under disease-free conditions genotypes YENYA-WOSO and CHINESE had the highest number of leaves atpod initiation and physiological maturity respectively

(Table S2) On the contrary ICGV-IS 13015 ICGV-IS 13071ICGV-IS 13079 ICGV-IS 13086 and ICGV-IS 13113 hadlower green leaf number than CHINESE at pod initiation Atphysiological maturity ICGV-IS 13045 and ICGV-IS 13114were the only two genotypes with similar number of leaves(pge 005) as CHINESE e rest of the genotypes had sig-nificantly (plt 005le 0001) lower leaf number than that ofCHINESE (Table S2) Furthermore genotype CHINESE hadthe highest leaf area (LA) at pod initiation but similar to thatof ICGV-IS 13081 ICGV-IS 13086 ICGV-IS 13018 ICGV-IS 13041 ICGV-IS 13052 ICGV-IS 13110 ICGV-IS 13114ICGV-IS 08837 ICGV-IS 13113 and ICGV-IS 13079(Table S2) However it had a leaf area which was higher thanthat of all the other genotypes including ICG 7878 andNKATIESARI

When plants were infected by the leaf spot diseasesCHINESE recorded the least pod yield of 223 tmiddothaminus1 whileNKATIESARI gave 618 tmiddothaminus1 as the highest (Table S3)Under disease-free conditions CHINESE and NKATIE-SARI gave similar pod yields of about 7 tmiddothaminus1e reductionin pod yield due to disease was highest in CHINESE(495 tmiddothaminus1) which was about 6454 of pod yield obtainedunder disease-free conditions (Table S3)

33 Relationship between the Stay-Green Trait (LAUG) LeafSpot Severity (AUDPC) Leaf Chlorophyll Content (SCMR)

Table 3 Area under disease progress curve for early leaf spot (ELS AUDPC) and late leaf spot (LLS AUDPC) diseases and leaf area undergreenness (LAUG) of 25 groundnut genotypes evaluated under disease and disease-free conditions in 2017

GenotypesELS AUDPC LLS AUDPC LAUG

Estimate Std error Sig Estimate Std error Sig Estimate Std error SigCHINESE (intercept) 21580 1171 lowastlowastlowast 20501 1654 lowastlowastlowast 5854dagger 341 lowastlowastlowast

GAF 1665 minus9661 1656 lowastlowastlowast minus8522 2068 lowastlowastlowast minus4043sect 417 lowastlowastlowast

GAF 1723 minus8857 1648 lowastlowastlowast minus6345 2031 lowastlowast minus3569sect 417 lowastlowastlowast

GK 7 minus5781 1656 lowastlowast minus3056 2068 ns minus3802sect 417 lowastlowastlowast

ICG 7878 minus9111 1655 lowastlowastlowast minus8223 2066 lowastlowastlowast minus3432sect 414 lowastlowastlowast

ICGV-IS 00064 minus7368 1656 lowastlowastlowast minus5057 2071 lowast minus3974sect 414 lowastlowastlowast

ICGV-IS 08837 minus820 1656 ns minus1204 2070 ns minus1139dagger 414 lowastlowastlowast

ICGV-IS 13015 minus5644 1656 lowastlowast minus4667 2071 lowast minus2416Dagger 417 lowastlowastlowast

ICGV-IS 13018 minus2336 1648 ns minus1213 2029 ns minus2217Dagger 414 lowastlowastlowast


ICGV-IS 13045 minus4271 1648 lowast minus6584 2030 lowastlowast minus2059Dagger 417 lowastlowastlowast

ICGV-IS 13052 minus4005 1648 lowast minus5020 2027 lowast minus2210Dagger 417 lowastlowastlowast


ICGV-IS 13078 minus3248 1655 ns minus4389 2067 lowast minus2286Dagger 417 lowastlowastlowast






ICGV-IS 13114 minus1682 1655 ns minus1225 2066 ns minus2958sect 414 lowastlowastlowast

ICGV-IS 13998 minus4833 1649 lowastlowast minus4612 2034 lowast minus3253sect 414 lowastlowastlowast

KPANIELI minus6980 1649 lowastlowastlowast minus5055 2032 lowast minus3514sect 414 lowastlowastlowast

NKATIESARI minus9833 1649 lowastlowastlowast minus8112 2034 lowastlowastlowast minus4077sect 417 lowastlowastlowast

SUMNUT 23 minus2708 1655 ns 959 2067 ns minus1400dagger 414 lowastlowastlowast

YENYAWOSO minus4218 1656 lowast minus6381 2069 lowastlowast minus1798Dagger 417 lowastlowastlowast

lowast lowastlowast and lowastlowastlowast indicate significance at 005 001 and 0001 levels of probability respectively ns not significant LLS late leaf spot ELS early leaf spot AUDPCarea under disease progress curve LAUG stay-green trait sect indicates stay-green genotype Dagger indicates moderately stay-green genotype dagger indicates non-stay-green genotype


Table 4 Leaf chlorophyll content (SCMR) of 25 groundnut genotypes evaluated under disease-free conditions

GenotypesSCMR at pod initiation SCMR at midpod filling SCMR at physiological maturity

Estimate Std error Sig Estimate Std error Sig Estimate Std error SigCHINESE (intercept) 2695 170 lowastlowastlowast 2874 194 lowastlowastlowast 3268 228 lowastlowastlowast

GAF 1665 800 232 lowastlowast 722 224 lowastlowast 180 233 ns

GAF 1723 506 232 lowast 331 224 ns 245 233 ns

GK 7 425 232 ns 145 224 ns 568 233 lowast

ICG 7878 253 226 ns 083 218 ns 211 227 ns

ICGV-IS 00064 139 226 ns minus004 218 ns 028 227 ns

ICGV-IS 08837 049 226 ns minus239 218 ns minus493 227 lowast

ICGV-IS 13015 454 232 ns 345 224 ns 176 233 ns

ICGV-IS 13018 minus074 226 ns minus145 218 ns minus013 227 ns

ICGV-IS 13041 128 232 ns minus289 224 ns minus328 233 ns

ICGV-IS 13045 042 232 ns 036 224 ns minus055 233 ns


ICGV-IS 13071 288 226 ns 059 218 ns 012 227 ns

ICGV-IS 13078 071 232 ns 358 224 ns 018 233 ns


ICGV-IS 13081 344 226 ns 232 218 ns 154 227 ns



ICGV-IS 13113 486 232 lowast minus009 224 ns minus111 233 ns

ICGV-IS 13114 295 226 ns 011 218 ns 115 227 ns


KPANIELLI 652 226 lowastlowast 525 218 lowast 378 227 ns

NKATIESARI 821 232 lowastlowastlowast 474 224 lowast 242 233 ns

SUMNUT 23 622 226 lowastlowast 571 218 lowast 257 227 ns

YENYAWOSO 371 232 ns 193 224 ns minus232 233 ns

lowast lowastlowast and lowastlowastlowast indicate significance at 005 001 and 0001 levels of probability respectively ns not significant SCMR leaf chlorophyll content

Table 5 Leaf chlorophyll content (SCMR) of 25 groundnut genotypes evaluated under disease conditions



GAF 1665 378 1672 lowast 280 2361 ns 512 2080 lowast

GAF 1723 411 1616 lowast 090 2298 ns 372 2029 ns

GK 7 519 1675 lowastlowast 162 2363 ns 419 2081 lowast

ICG 7878 142 1667 ns minus081 2356 ns 470 2076 lowast

ICGV-IS 00064 303 1680 ns 130 2368 ns 219 2085 ns


ICGV-IS 13015 166 1682 ns minus175 2369 ns 424 2086 lowast




ICGV-IS 13052 minus045 1605 ns minus478 2288 lowast minus271 2022 ns




ICGV-IS 13081 minus129 1676 ns minus193 2365 ns 167 2083 ns






KPANIELI 111 1622 ns minus041 2303 ns 495 2032 lowast

NKATIESARI 307 1626 ns 267 2306 ns 622 2035 lowastlowast

SUMNUT 23 409 1671 lowast minus164 2360 ns 097 2079 ns

YENYAWOSO 162 1675 ns minus194 2364 ns 029 2082 ns



Leaf Area (LA) and Pod Yield ere were significant cor-relations among all the traits considered (Table 6) Pod yieldhad negative correlation with LAUG (rminus068 plt 0001)ELS AUDPC (rminus062 plt 001) LLS AUDPC (rminus041plt 005) and LA (rminus068 plt 0001) Pod yield howeverhad strong and positive correlation with SCMR (r 070plt 0001) at pod initiation midpod filling (r 068plt 0001) and physiological maturity (r 058 plt 001)

On the contrary LAUG had strong and positive asso-ciations with LA at pod initiation (r 063 plt 0001) ELS(r 082 plt 0001) and LLS (r 063 plt 0001) AUDPCs(Table 6) Also LA at pod initiation had positive correlationswith ELS (r 079 plt 0001) and LLS (r 054 plt 001)AUDPCs

Results from the principal component analysis con-ducted using the AUDPCs of ELS and LLS gave clusters ofgenotypes that were similar to the stay-green (LAUG) classesobserved in Table 3 (Figure 1) Cluster ldquoArdquo was made up ofgenotypes that had stay-green except ICGV-IS 13015 whichexpressed moderately stay-green based on the LAUG pro-cedure Clusters ldquoBrdquo and ldquoCrdquo were made up of genotypeswith moderately stay-green while cluster ldquoDrdquo consisted ofnon-stay-green genotypes (Figure 1)

Using LAUG as a stay-green criterion to group thegermplasm nine genotypes were found to be stay-grain(SG) twelve moderately stay-green (MSG) and four non-stay-green (NSG) (Tables 3 and 7) Variance componentanalysis of the stay-green classes showed significant(plt 001) differences among the genotypes for LAUG ELSAUDPC LLS AUDPC and pod yield e stay-green classhad the lowest LAUG ELS AUDPC LLS AUDPC and thehighest pod yield (Table 7) while the non-stay-green classrecorded the highest LAUG ELS AUDPC LLS AUDPC andthe lowest pod yield e moderately stay-green class ofgenotypes was in between the two extreme classes (Table 7)

34 Genetic Analysis of the Stay-Green Trait

341 LAUG of Parents and F1 Generations SegregationRatios at F2 and Heritability Estimates of LAUG in thePopulation To understand the genetic basis of the stay-green trait two stay-green and two non-stay-green geno-types were crossed for further analysis Results of fieldevaluation of the parents together with the progeny showedthat CHINESE and ICGV-IS 13081 non-stay-green parentshad significantly (plt 001) the highest mean LAUG com-pared to that of NKATIESARI and ICG 7878 (Table 8) F1from ICGV-IS 13081timesNKATIESARI and CHINESEtimes ICG7878 crosses designated as SARGV 007 and SARGV 006respectively differed statistically from either parents andamong themselves Based on the stay-green classificationcriteria SARGV 006 was classified as stay-green whileSARGV 007 as moderately stay-green (Table 8)

e phenotypic variance was partitioned into the variouscomponents (Table 8) to estimate progress that can be re-alized through breeding e genetic component of thevariation (1898) was higher than that of the environment(317) Dominance was significantly higher (1694) than the

additive (204) genetic variances (Table 8) Heritability es-timates ranged from a low narrow sense heritability (h2009) to a very high broad sense heritability (H2 086)

Generation mean analysis of selected F1 progeny ad-vanced to F2 and evaluated for the stay-green trait showedthat there was no significant difference (pgt 005) betweenobserved and expected ratios at F2 based on the chi-squaretest (Table 9) e F2 population segregated in the ratio of 1(stay-green) 3 (non-stay-green)

4 Discussion

Biotic stresses such as disease infection reduce groundnutyield in many environments Despite considerable effortsdirected at fungicidal control of the disease in the guineaSavanna zone of Ghana [6] there is high incidence of leafspot diseases on farmersrsquo fields largely due to partial ef-fectiveness of chemical control measures [8] As a resultsustained maintenance of genetic progress in the im-provement of disease resistance is essential and this willrequire the identification and combination of new geneticvariation e AUDPC is a very convenient summary ofplant disease epidemics that incorporates initial intensitythe rate parameter and the duration of the epidemic whichdetermines final disease intensity [45] Based on the leaf spotseverity scores observed in this study genotypes GAF 1665GAF 1723 ICG 7878 and NKATIESARI were highly re-sistant to early and late leaf spot diseases Also stay-green(SG) moderately stay-green (MSG) and non-stay-green(NSG) genotype classes were found to have significantAUDPCs for ELS and LLS with SG class having the leastvalues is result depicts the resistance of the genotypes toleaf spot diseases e high level of leaf spot toleranceexhibited by the SG class might be due to their leaf char-acteristics such as thick palisade layer dark green colourand small stomata which have all been found to obstruct thegrowth of spores of Cercospora arachidicola and Cerco-sporidium personatum [46] It is therefore not surprising thatleaf chlorophyll content at pod initiation midpod filling andphysiological maturity all had strong negative correlationwith the AUDPCs of ELS and LLS conferring resistance tothe pathogens

Stay-greenness based on visual score of the proportion ofgreen leaf area maintained at physiological maturity hasbeen used as a criterion for selecting stay-green genotypes inmaize [19] sorghum [36] wheat [18 47] and sunflower [48]e significant differences observed among the groundnutgenotypes for LAUG in this study was due to the varieddegrees of leaf senescence at physiological maturity duringwhich the stay-green trait was expressed e observedgenotypic difference in the expression of the trait can beattributed to the different genetic backgrounds of the ge-notypes Borrell et al [28] that the stay-green trait is as-sociated with Stg QTL regulating canopy size throughconstraining the size of the upper leaves Genotypes thatexhibited lower rates of leaf senescence through physio-logical maturity (lower LAUG) were also observed to haverelatively smaller leave area Similar clustering patterns werealso observed when the genotypes were grouped based on


their AUDPC scores for ELS and LLS using principalcomponent analysis as opposed to using LAUG as a stay-green criterion Although CHINESE had the highest leafarea under greenness (highest rate of leaf senescence)

depicting non-stay-greenness it had the highest number ofleaves at pod initiation and physiological maturity underdisease-free conditions is suggests that in the absenceof leaf spot disease infections CHINESE is capable of

Table 6 Correlation between pod yield SCMR LA ELS AUDPC and LLS AUDPC

SCMR PI SCMR MPF SCMR PM Pod yield LLS AUDPC ELS AUDPC LA PILAUG minus072lowastlowastlowast minus074lowastlowastlowast minus084lowastlowastlowast minus068lowastlowastlowast 063lowastlowastlowast 082lowastlowastlowast 063lowastlowastlowastSCMR PI 092lowastlowastlowast 073lowastlowastlowast 070lowastlowastlowast minus048lowast minus08lowastlowastlowast minus079lowastlowastlowastSCMR MPF 078lowastlowastlowast 068lowastlowastlowast minus063lowastlowastlowast minus086lowastlowastlowast minus086lowastlowastlowastSCMR PM 058lowastlowast minus059lowastlowast minus075lowastlowastlowast minus059lowastlowastPod yield minus041lowast minus062lowastlowast minus068lowastlowastlowastLLS AUDPC 085lowastlowastlowast 054lowastlowastELS AUDPC 079lowastlowastlowastlowast lowastlowast and lowastlowastlowast indicate significance at 005 001 and 0001 levels of probability respectively SCMR leaf chlorophyll content LLS late leaf spot ELS early leafspot AUDPC area under disease progress curve LAUG stay-green trait PI pod initiation MPF midpod filling PM physiological maturity

PC2

(77

3)

SUMNUT 23

GK7

GAF 166

ndash10

ndash05

10

15

00

A

B

C

D

05

GAF 1723ICGV-IS 00064

ICGV-IS 13015ICG 7878

ICGV-IS 13086 ICGV-IS 13052


ICGV-IS 13045

ICGV-IS 13081

ICGV-IS 08837



ICGV-IS 13114

ICGV-IS 1971

ICGV-IS 13998

KPANIELI

NKATIESAF

YENYAWOSO

CHINESE

ELS

LLS

ndash10 05ndash00 10ndash15 ndash05PC1 (9227)

Figure 1 A plot of principal component analysis using the AUDPCs of ELS and LLS ldquoArdquo ldquoB and Crdquo and ldquoDrdquo denote stay-green moderatelystay-green and non-stay-green clusters respectively

Table 7 Comparison of different stay-green classes for pod yield LAUG ELS AUDPC and LLS AUDPC

Stay-Green Classes No of genotypes LAUG ELS AUDPC LLS AUDPC Pod yield (tmiddothaminus1)Stay-green (SG) 9 2217c 14480b 15083b 483a

Moderately stay-green (MSG) 12 3617b 18113a 16577b 361b

Non-stay-green (NSG) 4 4900a 20643a 20012a 319b

Means followed by different letters are significantly different at 005 probability level LAUG leaf area under greenness AUDPC area under disease progresscurve ELS early leaf spot LLS late leaf spot


replacing leaves which have been lost through naturalsenescence However in the presence of leaf spot diseaseinfections CHINESE loses this ability resulting in a re-duced number of leaves at physiological maturity com-pared to pod initiation stage

Crop maturity is usually characterized by senescencechlorophyll loss and a progressive decline in photosyn-thetic capacity However some genotypes exhibit de-creased or delayed chlorophyll catabolism [49] resultingin maintenance of their chlorophyll content for a longerperiod is phenomenon was portrayed in the groundnutpopulation used in this study During the reproductivephase genotypes that had lower LAUG also had relativelyhigher mean chlorophyll content at pod initiation mid-pod filling and physiological maturity Although therewas no significant difference among the genotypes for leafchlorophyll content during the reproductive phase var-iation among the genotypes increased as the crops ad-vanced towards physiological maturity with midpodfilling being the stage with the highest variance (resultsnot shown)is indicates that some genotypes (non-stay-green) were undergoing rapid leaf chlorophyll catabolismthan others (stay-green) and hence the lack of non-constant variance across the reproductive stage eseresults suggest that the most important stay-green classes(stay-green and non-stay-green) required to makebreeding progress are present in the population

However the genotypes performed differently under thedisease and disease-free conditions in pod yield withCHINESE being the worst affected under the disease con-ditions but became the best when there was no leaf spotdisease infection e percent reduction in pod yield due toleaf spot diseases in CHINESE was about 65 is high-lights the importance of leaf spot diseases as a major yieldreduction stress in groundnut production [4 5]

e strong positive relationship between LAUG andAUDPC for ELS and LLS suggest the possible influence of

the stay-green trait on leaf spot severity Also the ability ofthe AUDPC scores to segregate the genotypes into groupssynonymous to those of LAUG further highlights the in-terplay of these three traits in groundnut e results agreewith findings of different authors [49 50] who showed thatstay-green trait influences different diseases in other cropsFor instance sorghum recombinant inbred lines (RILs)carrying stay-green QTLs (stg1 stg3 or both (stg1 + 3))expressed high levels of resistance to Macrophomina pha-seolina and Fusarium thapsinum [50] Also the negativeassociation between LAUG and pod yield means selectingfor stay-greenness (lower LAUG) will enhance pod yieldis may be achieved either through reduced disease severityor enhanced photosynthetic activity of the plant via delay inchlorophyll catabolism [49] which results in prolonging theactive photosynthetic period e strong association be-tween LAUG pod yield and ELS and LLS AUDPC with leafchlorophyll content suggests that sustained leaf chlorophyllcontent during the reproductive phase is essential formaintenance of stay-greenness higher pod yield and highertolerance to leaf spot diseases in groundnut

e observed significant difference between the stay-green and non-stay-green parents for LAUG suggests thatgenetic differences existed between the parental lines usedfor the crosses e LAUG of the F1 generation was higherthan the midparent value and were closer to that of thenon-stay-green parents It is therefore possible that theallele controlling the non-stay-green trait is partiallydominant over the stay-green allele [43] e 1 3 segre-gation ratio of stay-green to non-stay-green genotypesobserved at F2 also indicates stay-greenness in groundnut iscontrolled qualitatively by a single recessive gene e traitcan therefore be expressed only when the two alleles are inthe same state Similar findings have been reported inwheat [51] and rice [52] However in maize it has beenreported that the stay-green trait is quantitatively inheritedwith 17 QTLs clustered on four chromosomes accounting

Table 9 Proportion of stay-green classes (segregation ratios) at F2

GenotypeObserved Expected

Stay-green Non-stay-green Stay-green Non-stay-green Total χ2 (1 3) p valueSARGV 006-1 2 8 25 75 10 0133 0715SARGV 008-1 3 10 325 975 13 0026 0873χ2 chi-square

Table 8 Leaf area under greenness of parents F1s and estimates of genetic variance components and heritability for stay-green trait

Means genotypes Mean LAUGVariance components and heritability

Genetic parameter LAUGCHINESE 4200plusmn 116a Phenotypic variance (VP) 2216ICGV-IS 13081 4200plusmn 001a Environmental variance (VE) 317SARGV 007 (F1) 3267plusmn 073b Genetic variance (VG) 1898SARGV 006 (F1) 2800plusmn 104c Additive variance (VA) 204NKATIESARI 1167plusmn 117d Dominance variance (VD) 1694ICG 7878 1050plusmn 001d Broad sense heritability (H2) 086Midparent value 2654 Narrow sense heritability (h2) 009Means followed by same letters are not statistically different


for 7308 of the total genetic variance [53] e higherbroad sense heritability compared to the narrow senseheritability observed for stay-green trait in the currentstudy implies that making selection from the existingpopulation will bring about more genetic advancementthan making crosses and selecting from the progenies [44]

5 Conclusion

e stay-green trait (LAUG) had a positive association withELS and LLS and hence has the ability to confer resistanceto leaf spot disease in groundnut Since it is relatively easierto score for this trait on a large number of entries groundnutbreeders can use this trait to select for ELS and LLS re-sistance in groundnut in areas with low disease pressureLeaf area at pod initiation and leaf chlorophyll at pod ini-tiation midpod filling and at physiological maturity can alsobe used to select for stay-green ELS and LLS resistance sincethere was a strong association between them Our resultsshow that stay-green trait in groundnut is under the controlof a single recessive gene Since the genotypes used wereadvanced breeding lines which have attained homozygosityat majority of their loci making selection from the existingpopulation will bring about more genetic gain due to thehigh broad sense heritability

Data Availability

Data used to support these findings and the analysis code canbe sourced from the corresponding author

Conflicts of Interest

e authors declare that they have no conflicts of interest

Acknowledgments

is work was supported by the Tropical Legume (TL) III(OPP1114827) and Alliance for a Green Revolution in Africa(AGRA) (2014 PASS 012)

Supplementary Materials

Table S1 number of green leaves (NGL) of 25 groundnutgenotypes evaluated under disease conditions Table S2 leafarea (LA) and number of green leaves (NGL) of 25groundnut genotypes evaluated under disease-free condi-tions Table S3 pod yield and its reduction due to ELS-LLSinfection of 25 groundnut genotypes evaluated under diseaseand disease-free conditions (Supplementary Materials)

References

[1] S Nedumaran P Abinaya P Jyosthnaa B Shraavya P Raoand C BantilanGrain Legumes Production Consumption andTrade Trends in Developing Countries ICRISAT ResearchProgram Markets Institutions and Policies PatancheruIndia 2015

[2] J Pasupuleti S N Nigam M K Pandey P Nagesh andR K Varshney ldquoGroundnut improvement use of genetic andgenomic toolsrdquo Frontiers in Plant Science vol 4 p 23 2013

[3] J Ndjeunga B R Ntare F Waliyar et al ldquoEarly adoption ofmodern groundnut varieties in West Africardquo 2008 httpoaricrisatorg2360

[4] S B akur S K Ghimire N K Chaudhary S M Shresthaand B Mishra ldquoVariability in groundnut (Arachis hypogaeaL) to Cercospora leaf spot disease tolerancerdquo InternationalJournal of Life Sciences Biotechnology and Pharma Researchvol 2 no 1 pp 254ndash262 2013

[5] A R Khan M Ijaz I U Haq A Farzand and M TariqjavedldquoManagement of Cercospora leaf spot of groundnut (Cerco-spora arachidicola amp Cercosporidium personatum) throughthe use of systemic fungicidesrdquo Cercetari Agronomice inMoldova vol 47 no 2 pp 97ndash102 2014

[6] S K NutsugahM Abudulai C Oti-Boateng R L Brandenburgand D L Jordan ldquoManagement of leaf spot diseases of peanutwith fungicides and local detergents in Ghanardquo Plant PathologyJournal vol 6 no 3 pp 248ndash253 2007

[7] J B Naab K J Boote P V V Prasad S S Seini andJ W Jones ldquoInfluence of fungicide and sowing density on thegrowth and yield of two groundnut cultivarsrdquo Journal ofAgricultural Science vol 147 no 2 pp 179ndash191 2009

[8] J B Naab S S Seini K O Gyasi et al ldquoGroundnut yieldresponse and economic benefits of fungicide and phosphorusapplication in farmer-managed trials in northern GhanardquoExperimental Agriculture vol 45 no 4 pp 385ndash399 2009

[9] S Pande R Bandyopadhyay M Blummel J Narayana RaoD omas and S S Navi ldquoDisease management factorsinfluencing yield and quality of sorghum and groundnut cropresiduesrdquo Field Crops Research vol 84 no 1-2 pp 89ndash1032003

[10] S C Leal-Bertioli A Jose D M Alves-Freitas et alldquoIdentification of candidate genome regions controlling dis-ease resistance in Arachisrdquo BMC Plant Biology vol 9 no 1p 112 2009

[11] P Subrahmanyam DMcDonald FWaliyar et al ldquoScreeningmethods and sources of resistance to rust and late leaf spot ofgroundnutrdquo 1995 httpoaricrisatorg3477

[12] A K Singh V K Mehan and S N Nigam ldquoSources ofresistance to groundnut fungal and bacterial diseases anupdate and appraisalrdquo 1997 httpoaricrisatorg6676

[13] B B Shew M K Beute and J C Wynne ldquoEffects of tem-perature and relative humidity on expression of resistance toCercosporidium personatum in peanutrdquo Phytopathologyvol 78 p 493 1988

[14] S N Nigam Groundnut at a Glance ICRISAT PatancheruIndia 2014

[15] S L Dwivedi S N Nigam R Jambunathan K L SahrawatG V S Nagabhushanam and K Raghunath ldquoEffect of ge-notypes and environments on oil content and oil qualityparameters and their correlation in peanut (Arachis hypogaeaL)rdquo Peanut Science vol 20 no 2 pp 84ndash89 1993

[16] C C Holbrook and W Dong ldquoDevelopment and evaluationof a mini core collection for the US peanut germplasmcollectionrdquo Crop Science vol 45 no 4 pp 1540ndash1544 2005

[17] H omas and C J Howarth ldquoFive ways to stay greenrdquoJournal of Experimental Botany vol 51 no 1 pp 329ndash3372000

[18] A K Joshi M Kumari V P Singh et al ldquoStay green traitvariation inheritance and its association with spot blotchresistance in spring wheat (Triticum aestivum L)rdquo Euphyticavol 153 no 1-2 pp 59ndash71 2007

[19] G Bekavac B Purar M Stojakovic D J JockovicM Ivanovic and A Nastasic ldquoGenetic analysis of stay-green


trait in broad-based maize populationsrdquo Cereal ResearchCommunications vol 35 no 1 pp 31ndash41 2007

[20] H omas and C M Smart ldquoCrops that stay greenrdquo Annalsof Applied Biology vol 123 no 1 pp 193ndash219 1993

[21] K D Subedi and B L Ma ldquoNitrogen uptake and partitioningin stay-green and leafy maize hybridsrdquo Crop Science vol 45no 2 pp 740ndash747 2005

[22] M O Adu D L Sparkes A Parmar and D O Yawson ldquoStaygreen in wheat comparative study of modern bread wheat andancient wheat cultivarsrdquo ARPN Journal of Agricultural andBiological Science vol 6 pp 16ndash24 2011

[23] S A Silva F I F de Carvalho J L Nedel et al ldquoAnalise detrilha para os componentes de rendimento de gratildeos em trigordquoBragantia vol 64 no 2 pp 191ndash196 2005

[24] M Antonietta H A Acciaresi and J J Guiamet ldquoResponsesto N deficiency in stay green and non-stay green argentineanhybrids of maizerdquo Journal of Agronomy and Crop Sciencevol 202 no 3 pp 231ndash242 2016

[25] J T Christopher M Veyradier A K Borrell G HarveyS Fletcher and K Chenu ldquoPhenotyping novel stay-greentraits to capture genetic variation in senescence dynamicsrdquoFunctional Plant Biology vol 41 no 11 pp 1035ndash1048 2014

[26] M S Lopes and M P Reynolds ldquoStay-green in spring wheatcan be determined by spectral reflectance measurements(normalized difference vegetation index) independently fromphenologyrdquo Journal of Experimental Botany vol 63 no 10pp 3789ndash3798 2012

[27] S Trachsel D Sun F M SanVicente et al ldquoIdentification ofQTL for early vigor and stay-green conferring tolerance todrought in two connected advanced backcross populations intropical maize (Zea mays L)rdquo PLoS One vol 11 no 3 ArticleID e0149636 2016

[28] A K Borrell E J vanOosterom J E Mullet et al ldquoStay-greenalleles individually enhance grain yield in sorghum underdrought by modifying canopy development and water uptakepatternsrdquo New Phytologist vol 203 no 3 pp 817ndash830 2014

[29] A Borrell G Hammer and E Oosterom ldquoStay-green aconsequence of the balance between supply and demand fornitrogen during grain fillingrdquo Annals of Applied Biologyvol 138 no 1 pp 91ndash95 2001

[30] A K Borrell G L Hammer and A C L Douglas ldquoDoesmaintaining green leaf area in sorghum improve yield underdrought I Leaf growth and senescencerdquo Crop Science vol 40no 4 pp 1026ndash1037 2000

[31] M KWanous F RMiller and D T Rosenow ldquoEvaluation ofvisual rating scales for green leaf retention in sorghumrdquo CropScience vol 31 no 6 pp 1691ndash1694 1991

[32] W K Atakora and P K Kwakye ldquoCarbon dioxide emissionfrom ferric luvisols the role of mineral nitrogen fertilizers andsoil temperature in the Guinea savanna agro-ecological zoneof Ghanardquo Journal of Agriculture and Ecology Research In-ternational vol 7 no 1 pp 1ndash17 2016

[33] R Oteng-Frimpong S P Konlan and N N DenwarldquoEvaluation of selected groundnut (Arachis hypogaea L) linesfor yield and haulm nutritive quality traitsrdquo InternationalJournal of Agronomy vol 2017 Article ID 7479309 9 pages2017

[34] R Oteng-Frimpong Y B Kassim R Danful R AkromahA Wireko-Kena and S Forson ldquoModeling groundnut(Arachis hypogaea L) performance under drought condi-tionsrdquo Journal of Crop Improvement vol 33 no 1 pp 125ndash144 2019

[35] J E Van Der Plank ldquoDynamics of epidemics of plant diseaserdquoInternational Journal of Pest Management Part B vol 11no 3 pp 307ndash317 1965

[36] W Xu D T Rosenow and H T Nguyen ldquoStay green trait ingrain sorghum relationship between visual rating and leafchlorophyll concentrationrdquo Plant Breeding vol 119 no 4pp 365ndash367 2000

[37] R Core Team R A Language and Environment for Statisticalcomputing (ldquoGreat Truthrdquo) R Foundation for StatisticalComputing Vienna Austria 2019

[38] D Bates M Maechler B Bolker et al Lme4 Linear Mixed-Effects Models Using ldquoEigenrdquo and S4 2019

[39] W-Y Loh ldquoSome modifications of levenersquos test of variancehomogeneityrdquo Journal of Statistical Computation and Sim-ulation vol 28 no 3 pp 213ndash226 1987

[40] A Kuznetsova P B Brockhoff and R H B ChristensenLmerTest Tests in Linear Mixed Effects Models 2019

[41] F de Mendiburu Agricolae Statistical Procedures for Agri-cultural Research 2019

[42] J Oksanen F G Blanchet M Friendly et al Vegan Com-munity Ecology Package 2019

[43] G Acquaah Principles of Plant Genetics and BreedingBlackwell Publishing Ltd Oxford UK 2007

[44] A R Hallauer M J Carena and J B M Filho QuantitativeGenetics in Maize Breeding Springer Science amp BusinessMedia Berlin Germany 2010

[45] L V Madden G Hughes and F Van Den BoschEe Study ofPlant Disease Epidemics American Phytopathological SocietySaint Paul MN USA 2007

[46] T A Coffelt and D M Porter ldquoField screening of reciprocalchicotimes florigiant peanut populations for resistance to leafspotin Virginiardquo Peanut Science vol 13 no 2 pp 57ndash60 1986

[47] M Kumari R N Pudake V P Singh and A K JoshildquoAssociation of staygreen trait with canopy temperature de-pression and yield traits under terminal heat stress in wheat(Triticum aestivum L)rdquo Euphytica vol 190 no 1 pp 87ndash972013

[48] A J de la Vega M A Cantore M M Sposaro N TrapaniM Lopez Pereira and A J Hall ldquoCanopy stay-green and yieldin non-stressed sunflowerrdquo Field Crops Research vol 121no 1 pp 175ndash185 2011

[49] H omas and H Ougham ldquoe stay-green traitrdquo Journal ofExperimental Botany vol 65 no 14 pp 3889ndash3900 2014

[50] A Adeyanju J Yu C Little et al ldquoSorghum RILs segregatingfor stay-green QTL and leaf dhurrin content show differentialreaction to stalk rot diseasesrdquo Crop Science vol 56 no 6pp 2895ndash2903 2016

[51] S A Silva F I F de Carvalho V de R Caetano et alldquoGenetic basis of stay-green trait in bread wheatrdquo Journal ofNew Seeds vol 2 no 2 pp 55ndash68 2001

[52] K-W Cha Y-J Lee H-J Koh B-M Lee Y-W Nam andN-C Paek ldquoIsolation characterization and mapping of thestay green mutant in ricerdquo Eeoretical and Applied Geneticsvol 104 no 4 pp 526ndash532 2002

[53] P R Belıcuas A M Aguiar D A V Bento T MM Camaraand C L de Souza Junior ldquoInheritance of the stay-green traitin tropical maizerdquo Euphytica vol 198 pp 163ndash173 2014


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Submit your manuscripts atwwwhindawicom

digestibility [9] when the haulms are fed to animals Leafspot disease occurs in two forms early leaf spot (ELS) whichis caused by Cercospora arachidicola S Hori (Berk andM ACurtis) and late leaf spot (LLS) caused by CercosporidiumpersonatumDeighton [10] Early leaf spot is characterized bylight brown spots surrounded by yellow halo while spots oflate leaf spot are black and usually without yellow halo [11]ELS and LLS typically occur together and their spread andseverity are influenced by the field cropping history tem-perature and relative humidity [12] e leaf spot diseaseepidemics are affected by weather patterns such as hot andwet conditions [13] Temperatures in the range of 25 to 30degCand high relative humidity favour infection and diseasedevelopment [14]

Efforts have been directed at chemical control of leaf spotdiseases in northern Ghana [6] However it has only beenpartially effective in controlling the disease on farmersrsquo fields[8] and substantially increases cost of production e de-velopment and adoption of leaf spot resistant cultivars willtherefore be a breakthrough to resource poor farmers in themiddle- and low-income countries [15] including Ghanawho cannot afford chemical control measures

Genetic variation exists in cultivated groundnut for bothELS and LLS resistance but the resistant genotypes aregenerally late maturing [16] Direct selection for leaf spotresistance in groundnut is also difficult and has been re-ported to be associated with low yield poor pod and kernelcharacteristics and late maturity [16] As a result there is theneed to consider other physiological traits that can confertolerance to the two foliar diseases and enhance pod andhaulm yields

Stay-green is an important trait that allows plants toretain their leaves in an active photosynthetic state whenexposed to stress conditions [17] It has been found to bepresent in different crops [17] and widely used in breedingfor disease resistance [18] e stay-green trait can be scoredon a large number of entries [19] and is associated with otherimportant agronomic and physiological traits It enablesplants to maintain active photosynthesis under drought [20]enhances higher nitrogen concentration in plant organs [21]confers tolerance to drought heat cold pathogens andresistance to lodging [22 23] and performs better under lownitrogen conditions [24] Maintenance of green leaf areathrough grain filling has been associated with increasedgrain yield in wheat [25 26] maize [27] and sorghum [28]e stay-green trait occurs at three levels in plants namelythe cell leaf and whole plant levels [29] However green leafarea at physiological maturity has proven to be a goodmeasure of stay-green [30 31] with the potential of en-hancing foliar disease resistance in groundnuts

e objectives of this study were to determine the (i)genetic control of the stay-green trait in groundnut and (ii)association between stay-green trait and leaf spots severity ingroundnut

2 Materials and Methods

21 Site Plant Materials and Design of Experiment eexperiment was carried out at the research station of Council

for Scientific and Industrial Research-Savanna AgriculturalResearch Institute (CSIR-SARI) Tamale Ghana located at09deg 25prime 41Prime N 00deg 58prime 42PrimeW and altitude of 183m above sealevel e study area is characterized by a relatively dryclimate with a unimodal rainfall ranging between 900 and1200mm annually e rainy season begins in May and endsin October with few scattered precipitation in Novembere soils of the area are Ferric Luvisols of the Tingoli series[32 33]

A total of 25 advanced breeding lines of groundnut withvaried levels of tolerance to leaf spot diseases were selectedfrom the germplasm collection at the CSIR-SARI (Table 1)ese lines comprised of four (4) released varieties andtwenty-one (21) advanced breeding lines assembled fromICRISAT EIR in Mali and INERA in Burkina Faso

e study comprised of two parts (i) evaluation of thegenotypes for the stay-green trait and leaf spot (ELS andLLS) severity and (ii) genetic analysis of the selected ge-notypes for stay-green trait

22 Evaluation of the Genotypes for the Stay-Green Trait andTolerance to Leaf Spot Diseases Evaluation of the 25 geno-types for leaf spot disease tolerance was done in the majorcropping season when the disease incidence is usuallyhighest Disease infection was done under natural conditionswith spreaders planted at border and between rows to ensureinoculum pressure for the disease development in 2016 Toensure zero incidence of the leaf spot diseases the genotypeswere evaluated for the stay-green trait in the minor season of2016

e experiment was laid in a partial lattice design withfive blocks replicated three times A plot comprised of fourrows of 4m long with inter- and intrarow spacing of 05mand 01m respectively One seed was planted per hill fol-lowing the procedure of Naab et al [7 8] e genotypeswere grouped into late medium and early maturing basedon the length of their maturity periods Hence plantingdates were staggered in the order of late medium and earlymaturing group respectively to ensure that their re-productive stages (stage of high disease infection) coincidedTriple superphosphate (TSP) was applied at a rate of 60 kgP2O5 haminus1 at two weeks after plantinge experiments werefurther supplemented with grounded oyster shells at a rate of200 kgmiddothaminus1 to supply calcium [34]

23 Genetic Analysis of the Stay-Green Trait in GroundnutAfter the field evaluation two groundnut genotypesexpressing the stay-green trait and resistance to leaf spotdiseases (NKATIESARI and ICG 7878) were selected andcrossed with two other genotypes CHINESE and ICGV-IS13081 that were non-stay-green and susceptible to leaf spotdiseases using a biparental mating design e F1 progenyfrom each cross divided into two sets one set was advancedto F2 whereas the other set was saved for field evaluation

e parents F1 and F2 were evaluated for leaf spotseverity and the stay-green trait during the major and minorseasons respectively in 2017 Spreaders were used to en-hance the disease inoculum pressure on the disease







AUDPC 1113944a

i1

Yi + Y(i+1)

21113896 1113897x t(i+1) minus ti1113872 11138731113890 1113891

LAUG 1113944a

i1

Si + S(i+1)

21113896 1113897x t(i+1) minus ti1113872 11138731113890 1113891

RPY PYdfp minusPYdp

(1)












δ2b 12VA +

14VD + VEC


δ2w 12VA +

34VD + VEW MS2

(3)



12VA

h2

VA

VA + VD + VEW

H2

VD

VA + VD + VEW

(4)


3 Results















































GAF 1723 506 232 lowast 331 224 ns 245 233 ns

GK 7 425 232 ns 145 224 ns 568 233 lowast

ICG 7878 253 226 ns 083 218 ns 211 227 ns



ICGV-IS 13015 454 232 ns 345 224 ns 176 233 ns





ICGV-IS 13071 288 226 ns 059 218 ns 012 227 ns

ICGV-IS 13078 071 232 ns 358 224 ns 018 233 ns


ICGV-IS 13081 344 226 ns 232 218 ns 154 227 ns




ICGV-IS 13114 295 226 ns 011 218 ns 115 227 ns











GAF 1723 411 1616 lowast 090 2298 ns 372 2029 ns



ICGV-IS 00064 303 1680 ns 130 2368 ns 219 2085 ns































4 Discussion








PC2

(77

3)

SUMNUT 23

GK7

GAF 166

ndash10

ndash05

10

15

00

A

B

C

D

05





ICGV-IS 13045

ICGV-IS 13081

ICGV-IS 08837



ICGV-IS 13114

ICGV-IS 1971

ICGV-IS 13998

KPANIELI

NKATIESAF

YENYAWOSO

CHINESE

ELS

LLS























5 Conclusion


Data Availability




Acknowledgments




References


























































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy









AUDPC 1113944a

i1

Yi + Y(i+1)

21113896 1113897x t(i+1) minus ti1113872 11138731113890 1113891

LAUG 1113944a

i1

Si + S(i+1)

21113896 1113897x t(i+1) minus ti1113872 11138731113890 1113891

RPY PYdfp minusPYdp

(1)












δ2b 12VA +

14VD + VEC


δ2w 12VA +

34VD + VEW MS2

(3)



12VA

h2

VA

VA + VD + VEW

H2

VD

VA + VD + VEW

(4)


3 Results















































GAF 1723 506 232 lowast 331 224 ns 245 233 ns

GK 7 425 232 ns 145 224 ns 568 233 lowast

ICG 7878 253 226 ns 083 218 ns 211 227 ns



ICGV-IS 13015 454 232 ns 345 224 ns 176 233 ns





ICGV-IS 13071 288 226 ns 059 218 ns 012 227 ns

ICGV-IS 13078 071 232 ns 358 224 ns 018 233 ns


ICGV-IS 13081 344 226 ns 232 218 ns 154 227 ns




ICGV-IS 13114 295 226 ns 011 218 ns 115 227 ns











GAF 1723 411 1616 lowast 090 2298 ns 372 2029 ns



ICGV-IS 00064 303 1680 ns 130 2368 ns 219 2085 ns































4 Discussion








PC2

(77

3)

SUMNUT 23

GK7

GAF 166

ndash10

ndash05

10

15

00

A

B

C

D

05





ICGV-IS 13045

ICGV-IS 13081

ICGV-IS 08837



ICGV-IS 13114

ICGV-IS 1971

ICGV-IS 13998

KPANIELI

NKATIESAF

YENYAWOSO

CHINESE

ELS

LLS























5 Conclusion


Data Availability




Acknowledgments




References


























































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy








δ2b 12VA +

14VD + VEC


δ2w 12VA +

34VD + VEW MS2

(3)



12VA

h2

VA

VA + VD + VEW

H2

VD

VA + VD + VEW

(4)


3 Results















































GAF 1723 506 232 lowast 331 224 ns 245 233 ns

GK 7 425 232 ns 145 224 ns 568 233 lowast

ICG 7878 253 226 ns 083 218 ns 211 227 ns



ICGV-IS 13015 454 232 ns 345 224 ns 176 233 ns





ICGV-IS 13071 288 226 ns 059 218 ns 012 227 ns

ICGV-IS 13078 071 232 ns 358 224 ns 018 233 ns


ICGV-IS 13081 344 226 ns 232 218 ns 154 227 ns




ICGV-IS 13114 295 226 ns 011 218 ns 115 227 ns











GAF 1723 411 1616 lowast 090 2298 ns 372 2029 ns



ICGV-IS 00064 303 1680 ns 130 2368 ns 219 2085 ns































4 Discussion








PC2

(77

3)

SUMNUT 23

GK7

GAF 166

ndash10

ndash05

10

15

00

A

B

C

D

05





ICGV-IS 13045

ICGV-IS 13081

ICGV-IS 08837



ICGV-IS 13114

ICGV-IS 1971

ICGV-IS 13998

KPANIELI

NKATIESAF

YENYAWOSO

CHINESE

ELS

LLS























5 Conclusion


Data Availability




Acknowledgments




References


























































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy











































GAF 1723 506 232 lowast 331 224 ns 245 233 ns

GK 7 425 232 ns 145 224 ns 568 233 lowast

ICG 7878 253 226 ns 083 218 ns 211 227 ns



ICGV-IS 13015 454 232 ns 345 224 ns 176 233 ns





ICGV-IS 13071 288 226 ns 059 218 ns 012 227 ns

ICGV-IS 13078 071 232 ns 358 224 ns 018 233 ns


ICGV-IS 13081 344 226 ns 232 218 ns 154 227 ns




ICGV-IS 13114 295 226 ns 011 218 ns 115 227 ns











GAF 1723 411 1616 lowast 090 2298 ns 372 2029 ns



ICGV-IS 00064 303 1680 ns 130 2368 ns 219 2085 ns































4 Discussion








PC2

(77

3)

SUMNUT 23

GK7

GAF 166

ndash10

ndash05

10

15

00

A

B

C

D

05





ICGV-IS 13045

ICGV-IS 13081

ICGV-IS 08837



ICGV-IS 13114

ICGV-IS 1971

ICGV-IS 13998

KPANIELI

NKATIESAF

YENYAWOSO

CHINESE

ELS

LLS























5 Conclusion


Data Availability




Acknowledgments




References


























































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy








GAF 1723 506 232 lowast 331 224 ns 245 233 ns

GK 7 425 232 ns 145 224 ns 568 233 lowast

ICG 7878 253 226 ns 083 218 ns 211 227 ns



ICGV-IS 13015 454 232 ns 345 224 ns 176 233 ns





ICGV-IS 13071 288 226 ns 059 218 ns 012 227 ns

ICGV-IS 13078 071 232 ns 358 224 ns 018 233 ns


ICGV-IS 13081 344 226 ns 232 218 ns 154 227 ns




ICGV-IS 13114 295 226 ns 011 218 ns 115 227 ns











GAF 1723 411 1616 lowast 090 2298 ns 372 2029 ns



ICGV-IS 00064 303 1680 ns 130 2368 ns 219 2085 ns































4 Discussion








PC2

(77

3)

SUMNUT 23

GK7

GAF 166

ndash10

ndash05

10

15

00

A

B

C

D

05





ICGV-IS 13045

ICGV-IS 13081

ICGV-IS 08837



ICGV-IS 13114

ICGV-IS 1971

ICGV-IS 13998

KPANIELI

NKATIESAF

YENYAWOSO

CHINESE

ELS

LLS























5 Conclusion


Data Availability




Acknowledgments




References


























































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy













4 Discussion








PC2

(77

3)

SUMNUT 23

GK7

GAF 166

ndash10

ndash05

10

15

00

A

B

C

D

05





ICGV-IS 13045

ICGV-IS 13081

ICGV-IS 08837



ICGV-IS 13114

ICGV-IS 1971

ICGV-IS 13998

KPANIELI

NKATIESAF

YENYAWOSO

CHINESE

ELS

LLS























5 Conclusion


Data Availability




Acknowledgments




References


























































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy








PC2

(77

3)

SUMNUT 23

GK7

GAF 166

ndash10

ndash05

10

15

00

A

B

C

D

05





ICGV-IS 13045

ICGV-IS 13081

ICGV-IS 08837



ICGV-IS 13114

ICGV-IS 1971

ICGV-IS 13998

KPANIELI

NKATIESAF

YENYAWOSO

CHINESE

ELS

LLS























5 Conclusion


Data Availability




Acknowledgments




References


























































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy


















5 Conclusion


Data Availability




Acknowledgments




References


























































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy





5 Conclusion


Data Availability




Acknowledgments




References


























































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy









































Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy





Journal of






Microbiology



Volume 2018



Volume 2018















BotanyJournal of










Agronomy




Documents

GeneticsofStay-GreenTraitandItsAssociationwithLeafSpot ...NIELLI;themoderatelystay-greengenotypeswereICGV-IS 13015, ICGV-IS 13018, ICGV-IS 13041, ICGV-IS 13045, ICGV-IS13052,ICGV-IS13071,ICGV-IS13078,ICGV-IS