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Field Crops Research 126 (2012) 145–151

Contents lists available at SciVerse ScienceDirect

Field Crops Research

jou rn al h om epage: www.elsev ier .com/ locate / fc r

ield evaluation of resistance to Colletotrichum truncatum in Lens culinaris, Lensrvoides, and Lens ervoides × Lens culinaris derivatives

. Vail ∗, J.V. Strelioff1, A. Tullu, A. Vandenbergrop Development Centre, 51 Campus Drive, University of Saskatchewan, Saskatoon, SK S7N 0L4, Canada

r t i c l e i n f o

rticle history:eceived 8 April 2011eceived in revised form 4 October 2011ccepted 4 October 2011

eywords:entilnthracnose

nterspecific

a b s t r a c t

Anthracnose, caused by Colletotrichum truncatum, is a major disease of lentil (Lens culinaris Medik.).Resistance to the more virulent race Ct0 of the pathogen is extremely rare within the cultivated L. culinarisgene pool and is limited to partial resistance. The secondary gene pool of L. culinaris, especially Lenservoides, is a source of resistance. Previously, a population of interspecific recombinant inbred lines wasdeveloped between susceptible L. culinaris line Eston and resistant L. ervoides L-01-827A; both resistantand susceptible stable lines were then identified in the population. A multi-year field trial in two differentdisease nurseries was conducted with the objectives of assessing relative resistance levels in the field andto evaluate the usefulness of field-nurseries for selecting resistance. A sub-set of the interspecific lines andL. culinaris and L. ervoides lines were evaluated which included eight resistant, eight partially resistantand four susceptible lines using a randomized complete block design with four replications per site

over two years. Results confirm that disease control can be obtained using L. ervoides-derived resistancegene(s) as under high disease pressure, some interspecific lines were significantly more resistant than themost resistant L. culinaris lines. Resistance ratings from disease nurseries were significantly correlated(0.69–0.90) with inoculations of both the virulent race Ct0 of C. truncatum and the less virulent race Ct1 onthe interspecific lines suggesting that field nurseries could effectively be used for selecting for resistancewithin a lentil breeding program.

© 2011 Elsevier B.V. All rights reserved.

. Introduction

In the past three decades, world-wide production of lentil haslmost tripled with 3.5 Mt production in 2008 (FAO, 2008). Withncreasing interest in the crop, disease is expected to continue as

major barrier to yield and product quality. In particular, anthrac-ose caused by Colletotrichum truncatum (Schwein.) Andrus & W.D.an cause significant yield loss and reduction of lentil seed qual-ty on the Canadian prairies and the northern plains of the USAChongo and Bernier, 2000a,b), especially if excessive moisture inate summer prolongs growth and delays harvest (Morrall et al.,

008). Yield losses of up to 28 and 57% on resistant and susceptible

ines, respectively, can occur under high disease pressure withouthe application of fungicide (Chongo et al., 1999).

Abbreviations: RIL, recombinant inbred line; NSF, North Seed Farm; rAUDPC,elative area under the disease progress curve.∗ Corresponding author. Present address: Agriculture and Agri-Food Canada, 107cience Place, Saskatoon, SK S7N 0X2, Canada. Fax: +1 306 956 7247.

E-mail address: Sally.Vail@agr.gc.ca (S. Vail).1 Present address: Bayer CropScience, Box 117 Site 600, R.R.#6, Saskatoon, SK S7K

J9, Canada.

378-4290/$ – see front matter © 2011 Elsevier B.V. All rights reserved.oi:10.1016/j.fcr.2011.10.002

Survival of the pathogen is aided by the development ofmicrosclerotia that remain in the field after harvest (Buchwaldtet al., 1996). Symptoms of anthracnose initially appear as superfi-cial lesions on young stems and leaves; when the crop reaches theearly flowering stage, premature leaflet abscission on lower leafletsoccurs. Given adequate rainfall, conidia form in acervuli on stemsand abscised leaflets and are splash-dispersed to uninfected tis-sue causing stem lesions to gradually move up the stem. Enlarginglesions can girdle stems and cause plants to wilt and die (Buchwaldtet al., 1996).

Two races of C. truncatum were identified (Buchwaldt et al.,2004) by using a host differential set of eight accessions to charac-terize 50 isolates of C. truncatum from Manitoba and Saskatchewan.Isolates designated as race Ct1 were avirulent on seven differ-entials whereas isolates designated race Ct0 were virulent on alldifferentials. Consequently, race Ct1 is considered less virulentthan Ct0, however races were found in equal proportions in thefield (Buchwaldt et al., 2004). Breeding for resistance in lentil toC. truncatum, especially to the highly virulent race Ct0, is of great

importance. Resistance to Ct1 within the Lens culinaris primarygene pool is abundant; however, resistance to race Ct0 is limited.Resistance to race Ct1 from the cultivar Indianhead, thought tobe conferred by a single recessive gene (Buchwaldt et al., 2001),

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46 S. Vail et al. / Field Crops

as been effectively transferred into cultivars such as CDC RobinVandenberg et al., 2002) and CDC Redberry (Vandenberg et al.,006). However, few cultivars or land races of L. culinaris haveeen identified with resistance to Ct0. Plant Gene Resources Canadacreened more than 1700 accessions from the Vavilov Institute anddentified VIR421, collected in Afghanistan by Barulina (1930), withartial resistance (Buchwaldt and Diederichsen, 2004; Vail andandenberg, 2010). Breeding lines from the cross 3155S have alsoemonstrated moderate resistance (Vail and Vandenberg, 2010);hese F2:3 family selections from the cross Yerli Kirmizi (‘local red’,

landrace grown extensively in Turkey)/CDC Redberry//CDC Red-erry were identified in an anthracnose disease nursery in 2005nd were developed using a form of cyclical recurrent selectiono enhance germplasm for minor resistance genes to anthracnoseMuehlbauer et al., 2009).

Wild relatives of crop species have been a valuable sourcef resistance in many pathosystems (Hajjar and Hodgkin, 2007).ens species in the secondary gene pool of cultivated lentil showesistance to race Ct0 and race Ct1 in both greenhouse and fieldxperiments (Tullu et al., 2006). These include lines of L. ervoidesgreatest frequency of resistance), L. lamottei, and L. nigricans. Theesistant plant L-01-827A, a selection from L. orientalis, accessionI 72847 but morphologically resembling L. ervoides with respecto leaflet number and morphology, flower size and seed diameters described by Fiala et al. (2009), was successfully crossed with. culinaris cultivar Eston, a small seeded, yellow cotyledon, greeneed coat, early maturing line released in Canada in 1980 (Slinkard,981). Eston is susceptible to anthracnose. This interspecific pop-lation, called LR59, was developed. LR59 included 85 stable F7:8

ines (Fiala et al., 2009). Investigation of resistance of LR59 recombi-ant inbred lines (RILs) to each C. truncatum race indicates the trait

s controlled by major genes and when the RIL LR59-81 was crossedith L. culinaris, resistance was shown to be dominant (Fiala et al.,

009; Vail and Vandenberg, 2011).Resistance in LR59 lines had not yet been tested under field con-

itions. In the current study, field characterization for resistanceo C. truncatum in LR59 RILs and select lines of L. culinaris and L.rvoides was performed across two sites and two growing seasons.he objectives were to determine the potential usefulness of theesistance genes from L. ervoides accession L-01-827A and to com-are the level of resistance with other sources of resistance found in. ervoides and L. culinaris, as well to evaluate the utility of nurserycreening for interspecific-derived resistance. The hypothesis washat interspecific-derived field resistance would be greater thanhat found within L. culinaris and that differentiation between resis-ant and susceptible lines would be possible under field nurseryonditions.

. Materials and methods

.1. Plant materials

Thirty lentil lines were evaluated at two sites in the 2006 and007 growing seasons. Fourteen F7:9 RILs and the parent lines fromhe interspecific cross Eston/L-01-827A (LR59) with differing lev-ls of resistance to race Ct0 and race Ct1 (Table 1; Fiala et al., 2009)ere assessed. Also included were four F2:4 (2006) or F2:5 (2007)

amilies from the cross 3155S (as shown in Table 1) along withhe parents, CDC Redberry and Yerli Kirmizi. Resistant and suscep-ible L. culinaris checks were also included to link the results torevious research on anthracnose resistance in lentil. The suscep-

ible check Pardina, a Spanish landrace grown in both Spain andhe Palouse area of the north-western USA, has been used as aniversal susceptible check for both ascochyta blight andnthracnose for many years. Partially resistant lines CDC Robin

rch 126 (2012) 145–151

(Vandenberg et al., 2002), VIR421 (Buchwaldt and Diederichsen,2004), and the cultivar Indianhead were also included along withfour additional accessions of L. ervoides (PI 72815 from Turkey,PI 72659 from Syria, and from unknown origin PI 72503 and PI116015) selected based on previous reports of varying anthracnoseresistance (Tullu et al., 2006). The L. ervoides accessions were allpart of the core collection obtained from the International Centerfor Agricultural Research in the Dry Areas, Syria. As the various linesevaluated were not consistent in their adaptation, yield data wasnot collected for any of the plots.

2.2. Disease nurseries, experimental design, and diseaseinoculation

Both sites for the field experiments were located in Saskatoon,Saskatchewan, at the North Seed Farm (NSF) and Preston Farmof the Department of Plant Sciences, University of Saskatchewan.The soil type of both sites is Dark Brown Chernozemic with theNSF being a fine sandy loam to loam texture (Bradwell Elstowassociation) and the Preston site being silt loam texture (ElstowHanley association). The Preston site is located approximately 2 kmof the NSF. The NSF site is an established lentil disease nursery;lentil breeding lines have been inoculated with the previous year’sinfested lentil stubble for more than 12 years and it is expectedthe established pathogen population consist of both races of C.truncatum. The NSF was seeded on May 25 in 2006 and May 17in 2007. The seeding date of the Preston site was June 2 in bothyears, deliberately delayed to create a contrasting environmen-tal effect based on precipitation pattern and crop development.The plots were arranged as a randomized complete block designwith four replications per site each year. Plots were single rows,75 cm long and with 30 cm between rows, with 20 seeds perplot planted approximately 2.5 cm deep with a row cone drill.Each plot was flanked with rows of both Eston (susceptible toboth races) and CDC Redberry (resistant to Ct1 and susceptible toCt0).

Plots were inoculated July 4 in 2006 and June 29 in 2007 withdiseased lentil straw collected from the NSF anthracnose nurserythe previous year. Misting irrigation was used to promote diseasedevelopment and commenced at the time of inoculation when theplants were in the late vegetative to early flowering phase at theNSF and were mid-vegetative at the Preston site. Irrigation was con-tinued till the first week of August or mid-August at the NSF andPreston sites, respectively. At the NSF, overhead sprinkler irrigationwith a spray diameter of 18.29 m with risers spaced for no water-ing overlap was applied at dusk for 15 min. Water pressure was60 psi applying approximately 0.01 mL/mm2 over the daily irriga-tion period. At the Preston site, a misting irrigation system usingMicro-BirdTM II Spinner SP16-340 (RainBird, CA) spaced 3.66 mapart ran for 15 min in the evening, twice overnight and early morn-ing at 40 psi applying 0.01 mL/mm2 per night. Each replication atall sites was surrounded by four rows of barley to prolong canopywetness throughout the day.

2.3. Disease evaluation and analysis

Whole plots were rated once a week throughout the epidemics,starting July 18 and July 25 in 2006 at the NSF and Preston sites fora duration of 38 and 48 days, respectively. In 2007, ratings startedJuly 13 and July 23 at NSF and Preston, respectively both for a dura-tion of 22 days (Fig. 1). The Horsfall and Barratt (1945) scale wasused to obtain percentage grade values for the amount of plant tis-

sue infected with disease. This scale is based on grades of diseasethat differ by a factor of two either side of 50% diseased tissue.The theory underlying the grades is that the human eye distin-guishes diseased or disease-free tissue according to the logarithm

S. Vail et al. / Field Crops Research 126 (2012) 145–151 147

Table 1Relative area under disease progress curves (rAUDPC) for lines of lentil evaluated in anthracnose nurseries at the North Seed Farm (NSF) and Preston sites in the 2006 and2007 growing seasons.

Line Species Controlledconditionscreeninga

2006 2007

Ct1 Ct0 NSFb Preston NSF Preston

LR59 interspecific recombinant inbred linesLR59-25 Le × Lc RILc HS S 49.2 HIJK 36.4 EFG 5.2 FGHIJK 1.1 FLR59-31 Le × Lc RIL HS HS 79.4 ABC 47.4 C 31.4 C 4.2 DEFLR59-33 Le × Lc RIL HS HS 66.3 CDEFG 39.3 DEF 8.6 FGHIJK 3.4 DEFLR59-36 Le × Lc RIL MS R 18.6 MN 10.9 NO 1.8 JK 2.5 DEFLR59-38 Le × Lc RIL R R 24.9 LMN 10.9 NO 1.8 K 1.7 DEFLR59-54 Le × Lc RIL R R 48.3 HIJK 15.8 LMN 3.1 GHIJK 0.9 FLR59-76 Le × Lc RIL MS MS 55.6 GHIJ 14.2 MN 5.7 FGHIJK 1.7 DEFLR59-80 Le × Lc RIL MR R 59.9 DEFGH 21.0 JKLM 4.5 FGHIJK 1.1 FLR59-81 Le × Lc RIL R R 39.7 JKL 20.5 KLM 2.9 HIJK 0.7 FLR59-87 Le × Lc RIL R R 32.5 KLM 1.8 P 2.0 IJK 2.0 DEFLR59-91 Le × Lc RIL HS HS 72.2 BCDEFG 45.1 CD 9.9 FGHI 2.3 DEFLR59-105 Le × Lc RIL HS S 68.6 BCDEFG 46.5 CD 11.2 EF 3.6 DEFLR59-132 Le × Lc RIL HS HS 73.6 BCDEF 43.3 CDE 22.9 D 3.2 DEFLR59-133 Le × Lc RIL HS MR 73.7 BCDE 43.3 CDE 18.5 DE 2.0 DEF

Commercial lentil cultivarsYerli Kirmizi Lc 96.3 A 79.9 A 69.5 A 17.8 BEston Lc 85.2 AB 58.8 B 39.8 B 9.0 CIndianhead Lc 63.6 CDEFGH 28.9 GHIJ 9.3 FGHIJ 4.0 DEFPardina Lc 95.7 A 74.9 A 63.2 A 16.9 BCDC Redberry Lc 71.5 BCDEFG 31.1 GHI 10.0 FGH 3.7 DEFCDC Robin Lc 75.4 BCD 35.0 FGH 17.9 DE 6.2 CDEVIR421 Lc 67.8 CDEFG 31.2 GHI 9.5 FGH 3.5 DEF

Lentil breeding lines3155S-1 Lc F4 or F5

d 64.0 CDEFGH 28.0 HIJK 10.4 FG 4.0 DEF3155S-5 Lc F4 or F5 56.1 FGHIJ 25.7 IJK 7.9 FGHIJK 4.8 CDEF3155S-6 Lc F4 or F5 68.6 BCDEFG 21.9 JKL 10.5 F 6.2 CD3155S-8 Lc F4 or F5 71.5 BCDEFG 36.4 EFG 9.6 FGH 4.3 DEF

Lens ervoides accessionsPI 72570-3 Le 42.1 IJK 2.9 P 3.0 HIJK 1.5 EFPI 116015 Le 96.3 A 81.7 A 70.3 A 22.7 API72659 Le 57.7 EFGHI 14.7 LMN 2.7 HIJK 2.1 DEFL-01-827A Le 39.5 JKL 16.8 LMN 3.0 GHIJK 1.3 FPI 72815 Le 10.5 N 4.9 OP 3.0 GHIJK 2.2 DEF

a As determined by Fiala et al. (2009) using the rating scale described by Buchwaldt et al. (2004).b Means within sites each year that are not followed by the same letter are significantly different (P < 0.05).

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c Lens ervoides accession L01-827A × Lens culinaris accession Eston recombinant id Yerli Kirmizi/CDC Redberry//CDC Redberry F2:4 (in 2006) or F2:5 (in 2007).

f light intensity. Percentage grade values were converted to Areander the Disease Progress Curve (AUDPC) values to quantify dis-ase progression over time where average percent between twodjacently timed ratings was multiplied by the number of daysetween when ratings were evaluated (Shaner and Finney, 1977).o compare different sites and years, AUDPC values were con-erted to relative AUDPC (rAUDPC) by dividing by the durationf the epidemic and multiplying the outcome by 100 as describedy Shtienberg et al. (2000). Values were analyzed as a combinedxperiment in the Mixed procedure in SAS (SAS Institute, Cary, NC)n a model where all factors were considered random (site, year,eplication within each site and year, and all interactions) exceptor Line, which was considered a fixed effect. The disease ratingsf the flanking resistant and susceptible check plots were addedo the statistical model as resistant and susceptible covariates todjust for within-block variability. Separate analyses by year andy each site within each year were performed for all lines as wells individual groups of lines (from the cross 3155S, L. culinaris, L.rvoides, and L. culinaris × L. ervoides RILs) using the Mixed proce-ure. Values for least square means were calculated independentlyithin each site by year combination. Standard errors of differences

nd P-values for differences between pairs of means of differentines were calculated using the PDIFF option in SAS and significantair-wise differences were converted to letter groupings (Saxton,998).

lines (RILs).

For the set of lines that were common to previous controlledcondition experiments performed in growth chambers by Fialaet al. (2009), Pearson correlation coefficients were calculated inSAS for average field disease ratings and previous ratings (con-verted to numerical grades of 1–6 for the different disease classes)which were inoculated separately with both races of the pathogen(Table 1; Fiala et al., 2009).

3. Results

Disease severity was greater in the 2006 vs. 2007 growing sea-son at both sites. In both years the NSF site had more disease thanPreston. As planned, the onset of flowering was delayed, on aver-age, by about two weeks at the Preston site compared to the NSFsite due to the difference in seeding dates. For example, Eston andRedberry checks started flowering June 30 to July 2 both years at theNSF and not till July 11–14 at the Preston site. Similarly, the begin-ning of the disease epidemic was delayed with the duration beingsimilar to the earlier seeded site. Highly significant differences wereobserved among lines in both seasons at both sites; covariates werehighly significant and greatly reduced the contribution of the site

years to overall variability (Table 2).

When all L. culinaris lines were considered, the ratings in 2006separated them into two groups (Table 1). Moderate resistance wasobserved in the group of cultivars classified as resistant to race

148 S. Vail et al. / Field Crops Research 126 (2012) 145–151

0

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Total Precip Max Te mp

Fig. 1. Weather data for Saskatoon: natural rainfall and maximum temperature; the brackets indicate the period of the epidemic. Note: Solid bracket indicates epidemic att

S

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he North Seed Farm and the dotted bracket the Preston site.

ource: Environment Canada, National Climate Data and Information Archive.

t1 (Indianhead, CDC Redberry and CDC Robin) compared to sus-eptible cultivars (Eston, Pardina, and Yerli Kirmizi) under modestisease pressure. The accession VIR421, identified by Plant Geneesources Canada as having some resistance to race Ct0, had fieldesistance similar to other L. culinaris lines previously establisheds race Ct1 resistant. Limited improvement in field resistance foramilies from the 3155S cross was observed compared to the recur-ent parent CDC Redberry. A small but significant improvement inhe family 3155S-5 over the race Ct1 resistant line CDC Robin wasbserved except in 2007 at the Preston site (Table 1). Minimal dif-erences among the four families of the 3155S cross were observedverall (Table 1).

When representative lines from each of the groups were com-ared (Table 1), the resistant LR59 RILs had significantly greateresistance than the most resistant L. culinaris lines (3155S-5,IR421, and CDC Redberry) which was especially evident under

reater disease pressure (NSF 2006). LR59-36 had significantlyess disease than the most resistant 3155S family (-5) as wells Ct1 resistant and susceptible lines. Another RIL, LR59-81, hadisease levels similar to 3155S-5. Between the two resistant

L. ervoides lines, significant differences were seen with less diseaseon PI 72815 than the LR59 parent L-01-827A (Table 1).

Differences in anthracnose ratings between lines from the LR59population were most evident under the higher disease pressurein 2006 as compared to 2007 (Tables 1 and 3). Some lines from theLR59 population (LR59-36, -38, -87, -81, -54, -76, and -80) demon-strated high resistance, similar to the L. ervoides parent L-01-827A.The susceptible RILs (LR59-31, -133, -132, and -91) had ratings sim-ilar to the susceptible parent Eston (Table 1). Similar to reports fromcontrolled conditions (Fiala et al., 2009), transgressive segregantsfor resistance or susceptibility were observed in the field for theLR59 population. rAUDPCs at each site in each year were signifi-cantly correlated with average ratings from controlled conditionscreening performed by Fiala et al. (2009) (Table 3). Best correla-tion to screening under controlled conditions with both races wasfound in 2006 at the Preston site which exerted the second great-

est disease pressure on the lines. Disease nursery conditions withthe greatest disease pressure showed only a slightly higher cor-relation than low disease pressure. However, the lack of diseasepressure in 2007 at the Preston site resulted in no differentiation of

S. Vail et al. / Field Crops Research 126 (2012) 145–151 149

Table 2Mixed model analysis of variance of disease ratings on lentil lines evaluated in anthracnose disease nurseries in the 2006 and 2007 growing seasons.

Source of variation Numerator degrees of freedom Denominator degrees of freedom F-Value P Estimate

CombinedLine 29 29.6 6.52 <0.01Susceptible covariate 1 344 38.86 <0.01Resistant covariate 1 279 61.82 <0.01Year 0Site 0Year × site 0Block (year × site) 0Year × line 353,323Site × line 0Year × site × line 711,941Residual 533,114

2006Line 29 29.4 14.46 <0.01Susceptible covariate 1 199 12.54 <0.01Resistant covariate 1 206 23.04 <0.01Site 0Block (site) 0Site × line 383,158Residual 856,836

2007Line 29 29 2.85 <0.01Susceptible covariate 1 81.6 10.06 <0.01Resistant covariate 1 107 0.23 0.63

Site 125,187Block (site) 307Site × line 1,030,608Residual 191,417

2006 North Seed FarmLine 29 85.3 13.32 <0.01Susceptible covariate 1 68 1.39 0.24Resistant covariate 1 39 0.60 0.44Block 7311Residual 1,425,239

2006 PrestonLine 29 86 58.49 <0.01Susceptible covariate 1 86 10.54 <0.01Resistant covariate 1 86 18.71 <0.01Block 0Residual 293,518

2007 North Seed FarmLine 29 88 56.92 <0.01Susceptible covariate 1 88 1.42 0.24Resistant covariate 1 88 0.06 0.81Block 0Residual 268,521

2007 PrestonLine 29 83 10.22 <0.01Susceptible covariate 1 59.5 8.52 <0.01Resistant covariate 1 69.8 1.15 0.29

rtie(

TCi

Block

Residual

esistance in the interspecific RILs (Table 1). Field testing in

he disease nurseries was equally correlated to results whennoculated with both races suggesting field conditions couldffectively screen for resistance to both races of C. truncatumTable 3).

able 3orrelations between relative area under disease progress curve values from field experi

nterspecific RIL lines inoculated with race Ct1 and race Ct0 of Colletotrichum truncatum.

Race Ct1

Correlationa

Average 0.85

North Seed Farm 2006 0.76

Preston 2006 0.90

North Seed Farm 2007 0.70

Preston 2007 0.69

a Pearson correlation coefficient.

1212107,128

4. Discussion

The greater disease severity in the 2006 vs. 2007 growing seasonwas most likely due to more consistent rainfall after inoculation in2006, which would have promoted fungal growth as well as spread

ments and data from controlled condition testing done by Fiala et al. (2009) of 14

Race Ct0

P Correlationa P

<0.01 0.81 <0.01<0.01 0.75 <0.01<0.01 0.84 <0.01<0.01 0.66 <0.01<0.01 0.71 <0.01

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f conidia by rain-splash. Higher temperatures in August also pro-onged the anthracnose epidemic in 2006; temperatures droppedelow optimal (20–24 ◦C) for disease development (Chongo andernier, 2000a,b) in August of 2007 (Fig. 1). In both years, the NSFite, which is believed to have more soil-borne inoculums becausef a much longer history of anthracnose inoculation activity, hadore disease than Preston. The delayed onset of flowering, by about

wo weeks at the Preston site compared to the NSF site, may havelso contributed to reduced disease as resistance declines at thenset of flowering (Chongo and Bernier, 2000a).

Field evaluation of newly identified L. culinaris lines with partialesistance to race Ct0 (families from the cross 3155S and VIR421)howed limited improvement of resistance over currently grownines. Based on observations in the anthracnose nursery in 2005data not shown), families from cross 3155S were expected to showmproved resistance over commercially available partially resistantines. Instead, only one family showed significant improvementver the race Ct1 resistant line CDC Robin (Table 1). Yerli Kirmiziroved highly susceptible (Table 1), demonstrating that its contri-ution to the resistance observed in cross 3155S families is minimalnd possibly limited to minor genes or downstream defence relatedathways triggered by resistance genes in CDC Redberry. The smallub-sample (four of approximately 75 3155S F2:3 families) mayave failed to capture the variability in the larger original popula-ion. Furthermore, susceptibility within each of the families wouldave been selected against in the growing season of 2005 whenriginally grown at the NSF under disease pressure. The partialesistance exhibited by cross 3155S families and VIR421 will beseful in creating resistant lines providing resistance is not linkedo deleterious traits that would negatively impact yield potential.ositive effects of partial resistance to anthracnose on reducingield loss are evident under high disease pressure; however, underow to moderate anthracnose pressure, as observed in the 2007rowing season of this study, partial resistance offered no benefitr detriment over susceptible cultivars.

Select interspecific RILs showed better resistance than what isurrently available in registered cultivars, indicating this source ofesistance could be effectively used to reduce the incidence andeverity of anthracnose in lentil crops in Saskatchewan. The L.rvoides accession PI 72815 had significantly less disease than theesistant parent L-01-827A (Table 1). This is consistent with aver-ge ratings of Tullu et al. (2006), who found PI 78215 to be onef the most resistant L. ervoides accessions. Interspecific RILs haveeen generated from a cross of PI 72815 and Eston with the aim ofransferring resistance genes from the wild accession PI 72815 to. culinaris (unpublished data).

Highly significant correlations between disease ratings at allites over both years and ratings under controlled conditionsuggests that field evaluations of resistance accurately reflect resis-ance to both races in this population even under lower diseaseressure. Chongo and Bernier (1999) reported significant corre-

ations between field inoculations and disease screening underontrolled conditions for various components of partial resistance.iven that resistance derived from L-01-827A is either controlledy the same gene(s) or by genes that are tightly linked (Vail andandenberg, 2011), the fact that results observed in this study ofeld inoculations with a population of Mixed races correspond withata from controlled condition inoculations with individual racesFiala et al., 2009) is not surprising. These results confirm that selec-ion for resistance in segregating populations, where L. ervoides line-01-827A has been used as a source of resistance, can effectivelye performed using field disease nurseries.

Selection for resistance derived from L-01-827A based on singlelants at the F2 and F3 is now regularly employed at the NSF. Theesults presented here indicate that single plant selections may beffective; however the presence of resistance should be assessed in

rch 126 (2012) 145–151

later generations when replicated trials and controlled conditionscreening experiments are possible. Additionally, special consider-ation should be given to populations that are selected in years withlower disease pressure. Chongo and Bernier (1999) suggest thatAUDPC values from the field are useful for comparing and selectingresistant lines, but suggested more than two years of testing may berequired when evaluating components of partial resistance underfield conditions. Currently, advanced trial entries are screened forrace Ct1 resistance in replicated experiments under controlled con-ditions. As breeding lines with L. ervoides-derived resistance genesnear the latter portion of the breeding cycle, controlled conditionscreening with race Ct0 may be useful for selecting potential vari-eties between various families and for selecting breeder seed lineswithin the selected families.

Breeding for resistance to the highly virulent race Ct0 of C.truncatum is of the utmost importance for lentil production inCanada and the USA. Overall, L. ervoides-derived resistance toanthracnose demonstrated the highest level of field resistancein this study, especially under higher disease pressure. Useful-ness of the introgressed resistance genes appears most evident inseasons conducive to anthracnose development. Based on theseresults, selection for resistant plants from F2 disease nurseriesshould be complemented with controlled condition testing atanother generation because field seasons with non-conduciveconditions for anthracnose may not fully amplify differences.Based on, in part, the results of this study, continued invest-ment into introgression of resistance genes from L. ervoidesaccession L-01-827A into cultivated lentil was warranted. To fur-ther facilitate selection for resistance derived from L. ervoides,molecular markers for the intogressed chromosomal segments con-taining interspecific-derived resistance is underway using singlenucleotide polymorphisms.

Acknowledgements

Funding was generously provided by the Saskatchewan PulseGrowers and the Robert P. Knowles Scholarship. The authors areextremely grateful for technical assistance provided by B. Barlow,K. Blomquist, S. Ife, T. Prado, and M. Thompson and the editingassistance of G. Binsted.

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