Spodoptera litura F. induced cross-resistance against microbial pathogens in Capsicum annuum L.

Abstract

Herbivory by Spodoptera litura (F) larvae stimulate the production of induced defense in chili plants as a defense response. The induced defense response of the plant causes change in the secondary metabolites. The present study was conducted hypothesizing the role of pest induced defense in inhibiting the successive invading pathogens (Cross-resistance) in chili plants. Bioassay studies were conducted to test our hypothesis and observed herbivory significantly reduced invasion of the bacterial pathogen, Xanthomonas campestris pv. Vesicatoria. As the phenolic acids in the plants are known to possess antimicrobial properties we presumed the role of S. litura induced phenols in inhibiting the bacterial growth in chili plants as well. An in vitro agar dilution assay was conducted to identify the effective phenolic compound with antimicrobial nature by evaluating the minimum inhibitory concentrations. Overall, syringic acid was found to be effective in inhibiting X. campestris pv. vesicatoria growth, as indicated by low minimum inhibitory concentrations (MICs). The results indicate the cross-resistance role of herbivory induced secondary metabolites.