BIOCHEMICAL AND MOLECULAR MECHANISMS OF RESISTANCE TO Helicoverpa armigera (Hubner) IN WILD RELATIVES OF CHICKPEA
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Date
2017
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Acharya N.G. Ranga Agricultural University
Abstract
The present studies on “Biochemical and molecular mechanisms of resistance
to Helicoverpa armigera (Hubner) in wild relatives of chickpea” were carried out
at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT),
Patancheru, during 2014-16. A total of 20 accessions (15 wild relatives and five
varieties of cultivated chickpea) were used to evaluate the mechanism of resistance
to H. armigera. Under field conditions, during post-rainy seasons 2014-15 and
2015-16, all genotypes of wild relatives of chickpea recorded less number of
H. armigera larvae, low visual leaf damage rating and per cent pod damage
compared to cultivated chickpea.
The genotypes IG 70012, PI 599046, IG 70022, PI 599066, IG 70006, IG
70018 (Cicer bijugum), ICC 506EB, ICCL 86111 (resistant checks), IG 72933, IG
72953 (C. reticulatum) IG 69979 (C. cuneatum) and IG 599076 (C. chrossanicum)
showed high levels of antixenosis for oviposition of H. armigera under multi-,
dual- and no-choice cage conditions.
Studies on detached leaf assay revealed that the genotypes IG 70012, IG 70022,
IG 70018, IG 70006, PI 599046, PI 599066 (C. bijugum), IG 69979 (C. cuneatum),
PI 568217, PI 599077 (C. judaicum) and ICCW 17148 (C. microphyllum) showed
less damage rating and low larval weights compared to susceptible checks. Larval
survival was greater on the wild relatives than on the cultivated chickpea. Detached
pod assay studies revealed that all wild relatives of chickpea exhibited less damage
rating, lower per cent pod damage and lower percentage of weight gained by thirdinstar
larva compared to cultivated chickpea.
Survival and development of H. armigera on artificial diet impregnated
with lyophilized leaf powders revealed that all wild relatives of chickpea
genotypes showed high levels of antibiosis to H. armigera compared to cultivated
chickpea in terms of lower larval survival, per cent pupation and adult emergence,
decreased larval and pupal weight, prolonged larval and pupal developmental
periods and reduced fecundity.
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Among morphological characters, glandular and non-glandular trichomes
showed negative association with oviposition under multi-choice and no-choice
conditions. Glandular trichomes had significant negative association with damage
rating, whereas non-glandular trichomes had significant positive association with
damage rating and larval weight but negative association with larval survival in
detached leaf assay. Pod wall thickness showed significant negative association
with damage rating and per cent pod damage in detached pod assay.
HPLC finger prints of leaf organic acids revealed a negative association of
oxalic acid with oviposition, while malic acid showed positive and significant
association with oviposition under multi- and no-choice conditions. Oxalic acid
and malic acid had significant and negative correlation with larval survival in
detached leaf assay, which indicates that higher amounts of these acids in
cultivated chickpea resulted in reduced larval survival compared to wild relatives.
The flavonoid compounds viz., chlorogenic acid, ferulic acid, naringin, 3, 4-
dihydroxy flavones, quercetin, naringenin, genestein, formononetin and biochanin A
identified through HPLC finger prints exhibited negative effects on survival and
development of H. armigera reared on artificial diet impregnated with lyophilized
leaf powders. Proteins and phenols showed negative effect, while tannins and total
soluble sugars showed positive effect on survival and development of H. armigera
reared on artificial diet with lyophilized leaf powders of wild relatives of chickpea.
Zymogram analysis revealed presence of 3 to 7 trypsin inhibitor (TI)
isoforms in all 20 genotypes. The genotypes, IG 70018, IG 70012, IG 70006, IG
70022, PI 599066, IG 72933, IG 72953 and IG 69979 showed higher inhibitory
activity of H. armigera gut (HG) proteases, while genotypes PI 510663, PI
599109, PI 568217 and ICCW 17148 showed low inhibitory activity under in vitro
conditions. Studies on hemagglutination of lectins revealed that wild relatives of
chickpea genotypes showed more agglutination even at less concentration. Schiff’s
base staining of lectins revealed that only one isoform with a molecular weight of
29 kDa was observed in wild relatives of chickpea.
GC-MS profile peaks of leaf surface chemicals identified with hexane
extracts showed 56 peaks in all genotypes. Correlation studies with detached leaf
assay and oviposition preference indicated presence of feeding and oviposition
repellents as well as phagostimulants and oviposition attractants. A total of 107
GC-MS profile peaks were identified with methanol extracts. Correlation studies
indicated that methanol extracts had higher amount of phagostimulants and
oviposition repellents than antifeedants and oviposition attractants.
The 26 SSR markers used for assessing genetic diversity of wild relatives
of chickpea detected a total of 186 alleles with an average of 7.15 alleles per
marker. PIC values varied from 0.21 (CaM2064) to 0.89 (CaM0958, ICCM0249
and TAA58). Gene diversity varied from 0.24 (CaM2064) to 0.90 (CaM0958,
ICCM0249 and TAA58). The average observed heterozygosity was 0.20.
The dendrogram based on UPGMA showed that cultivated chickpea
showed a closer genetic relation with the C. reticulatum, while, the species C.
microphyllum, C. judaicum, C. bijugum and C. pinnatifidum were placed in other
cluster. The other species C. cuneatum was placed in separate cluster indicated
that it is distantly related to species in other two clusters.
Description
D5512
Keywords
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