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Host plant resistance against insect pests
in pepper and tomato
Ben Vosman
Asian Solanaceous Round Table 2017
Why insect resistance research
� Direct damage
● Through feeding
● Honeydew, molds
� Indirect damage
● Virus transmission
� Yield and quality loss
� Problems increase
● Ban on insecticides
● Climate change
host plant resistance
How do plants defend themselves
Direct defense
physical and/or chemical traits
Indirect defense
Volatiles
predators
parasitoids Growth rate
Reproduction
Mortality
Focus of our research: Sap feeding insects
� Phloem feeders
● Whiteflies
● Aphids
� Cell content feeder
● Thrips
Aims of our research
� Identification of new sources of resistance
● Germplasm screens
� Characterization of the resistance
● Bioassays (population development, choice – no-choice experiments, behavior studies), Metabolomics
� Molecular markers + genes
● Segregating populations
● Genomics, candidate genes
� Resistance mechanism
Germplasm screens
� Solanaceae
● Aphid resistance in potato and pepper
● Thrips resistance in pepper
● Whitefly resistance in tomato and pepper
� Brassica
● Thrips, cabbage aphid, rootfly and whiteflyresistance in cabbage
� Others
● Thrips resistance in onion and leek
● Aphids in lettuce and lily
Several good sources identified
Resistance often present in CWR
Characterization of the resistance
� Thrips resistance in pepper
● Identification of sources
● Effect on different life stages of thrips
● QTL mapping of thrips resistance and metabolites
� Insect resistance in tomato
● Identification of sources
● QTL mapping
● Chemical characterization
Screening of pepper for thrips resistance
screenhouse glasshouse
cuttingleafLeaf disc
Good sources identified
Survival rate of immature states on pepper
Maharijaya, et al. (2012) EEA 145:62%71
QTL mapping
� F2 population, 196 individuals
● R female: C. annuum AC 1979
● S male: C. chinense 4661
� Phenotyped for thrips resistance and metabolites
QTL for thrips resistance
P14M48-3230.0
E32M49-40619.8
E32M49-52048.9E35M58-44653.6E35M58-28061.1HmpsE11371.2Hpms1_577.7Epms_37679.9
HpmsE078108.1
HpmsAT2-20123.7P17M32-227129.1
P11M48-159148.4
HpmsE088168.0
HpmsE014181.0
E35M49-332197.4
damage
surv.L2
surv.pupa0 5
10
15
20
25
30
P06
42% – 51%
explained variance
Maharijaya, et al. 2015 TAG 128:1945–1956
Metabolites correlated with larval survival
P14M48-3230.0
E32M49-40619.8
E32M49-52048.9E35M58-44653.6E35M58-28061.1HmpsE11371.2Hpms1_577.7Epms_37679.9
HpmsE078108.1
HpmsAT2-20123.7P17M32-227129.1
P11M48-159148.4
HpmsE088168.0
HpmsE014181.0
E35M49-332197.4
damage
LC2703
LC6636
surv.L2LC
3072
LC2514
surv.pupaO
ctacosane
Capsianoside-III
GC
1607
LC5046
GC
2054
GC
19100 5
10
15
20
25
P06
Capsianoside and unknown compound LC5046:corr with resistance;Co-localization but no known effects on insects
Maharijaya, et al. unpublished
Conclusions on thrips resistance
� Good resistance sources identified
� Resistance blocks larval development
� Based on one major QTL
� Some metabolites correlate and co-locate with resistance
● Unclear if they are causal
Insect resistance in tomato
� Screening Lycopersicon group of Solanum sectionLycopersicon for insect resistance
● S. lycopersicum
● S. pimpinellifolium
● S. cheesmaniae
● S. galapagense
� Characterization of resistance
● QTL mapping
● metabolomics
Pest insects used:
● Whitefly: Trialeurodes vaporariorum
● Aphid: Myzus persicae
● Caterpillar: Spodoptera exigua
● Thrips: Frankliniella occidentalis
Resistance parameters and correlations
whitefly survival wh
i te
f ly s
urv
i va
l
wh
i te
f ly o
vip
os i
tio
n
thr i
ps
surv
i val d
ay
2
thr i
ps
surv
i val d
ay
3
thr i
ps
surv
i val d
ay
4
cat e
r pilla
r su
r viv
al
cat e
r pilla
r w
eig
ht
ap
hid
su
r viv
al
whitefly oviposition 0.89
thrips survival day 2 0.62 0.57
thrips survival day 3 0.70 0.55 0.63
thrips survival day 4 0.60 0.39 0.41 0.78
caterpillar survival 0.51 0.36 0.24 0.46 0.65
caterpillar weight 0.38 0.43 0.32 0.29 0.30 0.82
aphid survival 0.74 0.77 0.38 0.64 0.57 0.44 0.40
aphid nymphs 0.41 0.60 -0.03 0.29 0.26 -0.02 0.02 0.68
S. pimpinellifolium (5 acc.)
S. cheesmaniae (3 acc.)
S. galapagense (3 acc.)
Reference materials (4 acc.)
Overview survival data
S. habrochaites
S. cheesmaniae
S. galapagense
cv. Moneymaker
S. pimpinellifolium
S. pennellii
Whitefly Thrips Caterpillar Aphid
LA716 a LA716 a PV110096 a PV110083 a
PV110114 ab PV110114 ab PV110118 a PV110114 a
LA1777 bc PV110083 abc LA1777 a LA716 a
PI134418 c PV110059 abcd PV110083 a LA1777 a
PV110083 d PI134418 abcd PV110114 a PI134418 a
PV91102 de LA1777 abcd PI134418 a PV91102 a
PV110118 de PV110118 bcd PV110112 a PV110118 a
PV110059 ef PV110096 bcd PV110086 a PV110059 b
cv. MM ef PV110112 bcd LA716 a PV110057 bc
PV110061 ef PV110086 bcd PV110057 b PV110096 bc
PV110112 ef PV110061 cd cv. MM bc cv. MM bcd
PV110096 ef PV110057 cde PV91102 b PV110061 cd
PV110057 ef PV91102 de PV970017 d PV110112 de
PV110086 f cv. MM e PV110059 cd PV970017 e
PV970017 f PV970017 e PV110061 d PV110086 e
Trichomes
All accessions resistant against whitefly, aphids and thrips had trichomes type IV.
� No correlation was found between PS and the presenceof trichome type I or IV, suggesting a different mechanism at this level
I
IV
VI
Metabolomics on the accessions
� Comparing metabolites among the lycopersicon group accessions
� 2 bulks of each 3 plants
� LCMS analysis
● Untargeted
● Analysis focused on acyl sugars
� 2565 metabolites detected among 11 accessions
PCA analysis of the accessions
Based on all metabolites
S. cheesmaniaeS. galapagenseS. pimpinellifoliumcv. Moneymaker.
Acyl sugars are partly species specific
Heatmap shows the 229 acyl sugars detected
LA716
LA716
LA1777
LA1777
PI134418
PI134418
MM
PV110057
PV110057
MM
PV110096
PV110086
PV110061
PV110061
PV110086
PV110096
PV110112
PV970017
PV110112
PV110114
PV110114
PV110083
PV110083
PV110118
PV110118
PV110059
PV110059
PV091102
PV091102
F2 population created
� Several sources for good whitefly resistance available in S. galapagense and S. pimpinellifolium.
� Further analysis using F2 populations
● S. galapagense and S. lycopersicum
● Phenotyped in the Netherlands and Indonesia for B. tabaci resistance
● Genotyped using a SNP array
QTL Mapping
� Large effect QTL found on chromosome 2 for Adult survival, Oviposition rate and trichome type, all at thesame position
� Additional minor QTLs for Adult survival and Oviposition rate on chromosome 9
� 54% of AS explained
0
5
10
15
20
0 20 40 60 80 100 120 140 160
LOD ScoreChromosome 2
Firdaus et al 2013 TAG 126:1487-1501
Acyl sugars in 10 R and 10 S plants of F2
Conclusions on insect resistance in tomato
� The S. galapagense accessions are resistant against several insects.
� S. pimpinellifolium accessions differ in resistance. Some show resistance, others are susceptible.
� S. cheesmaniae accessions are generally susceptible towards insects.
� There is a huge variation in metabolites among the accessions, some correlated to resistance
� Analysis of an F2 population showed a major QTL for whitefly survival on chromosome 2
General Conclusions
� Good resistance sources identified in several crops
● Resistance often present in (old) landraces and Crop Wild Relatives
● More emphasis on conservation of CWR needed
� Resistance mechanisms still largely unclear
● Different mechanisms in different crops
● Trichomes – no trichomes
� Good perspectives for resistance breeding
Acknowledgements:
WUR Plant Breeding
� Roeland Voorrips
� Olga Scholten
� Sjaak van Heusden
� Koen Pelgrom
� Greet Steenhuis-Broers
� Betty Henken
� Martijn van Kaauwen
� Wendy van ‘t Westende
Former PhD students
� Colette Broekgaarden
� Awang Maharijaya
� Syarifin Firdaus
� Alejandro Lucatti
WUR Entomology
� Joop van Loon
WUR Bioscience
� Ric de Vos
Sponsors: