Characterization of Eggplant Genotypes for Different Resistance Mechanisms Against Leucinodes orbonalis

Host plant resistance mechanisms play an important role in developing cultivars with resistance to the target pests; information regarding morphological and biochemical factors contributing to the resistance is essential for developing pest-resistant cultivars. As a result, we investigated the contribution of various morphological and biochemical characters in forty-two eggplant genotypes against Leucinodes orbonalis Guenée, in Himachal Pradesh, India. Out of all the phenotypic parameters evaluated, pericarp thickness (r = 0.89) has significantly positive correlation with fruit infestation, whereas trichome density had significantly negative correlation (r = - 0.89). Analysis of the biochemical compounds in the eggplant genotypes revealed that total phenols (r = - 0.71), polyphenol oxidase (r = - 0.63), peroxidases (r = - 0.35), phenylalanine ammonium lyase (r = - 0.71) and solasodine (r = - 0.81) had significantly negative correlation with the per cent fruit infestation by L. orbonalis while the reducing sugars (r = 0.66) and non-reducing sugars (r = 0.62) showed a significantly positive correlation. Molecular characterization by random amplified polymorphic DNA (RAPD) primers also revealed the presence of high genetic diversity among different eggplant genotypes, where 17 polymorphic RAPD primers produced a total of 167 amplicons, among which 144 amplicons were polymorphic and 23 monomorphic bands. PCR-amplified DNA fragment size ranged from 100 to 2500 bp, mean polymorphism was 86.42% and the average PIC value was 0.444. Jaccards coefficient-based dendrogram grouped 40 eggplant genotypes into two major clusters. Results also revealed that the resistant genotypes accumulated higher levels of defensive biochemical enzymes such as phenols, PO, PPO, PAL and solasodine to confer insect resistance. Molecular characterization also revealed that genotypes in the present study were genetically diverse and could be used in future breeding and improvement programmes in this crop. Genotypes, IC411485 and IC090951, in particular, can be used as varied parents in breeding programmes to generate improved lines in terms of resistance to L. orbonalis.