Abstract:
Plant defense signaling involves a complex network of interacting signals majorly
regulated by phytohormones. A large number of studies have shown the critical role
played by the phytohormones jasmonic acid (JA), salicylic acid (SA), ethylene (ET)
and abscisic acid (ABA) in this However; all these studies have been majorly limited
to the context of folivory (leaf eating herbivory) although there are many other
interactions present in nature. One such interaction is frugivory (fruit herbivory) of
eggplant: Solanum melongena (Solanaceae) by the specialist insect herbivore
Leucinodes orbonalis Guenee [shoot and fruit borer (SFB), Lepidoptera: Pyrallidae].
Eggplant, being one of the most important vegetable crops in Asia faces major threat
from SFB, with infestation potential to the extent of 70 to 93 percent. None of the
pest management strategies employed in field offered resistance to SFB to an
adequate level. The chemistry of plant-insect interaction in this case is poorly
understood. In this study, we report the involvement of two phytohormones ABA and
ET in eggplant fruit response towards SFB attack. Our results show the increased
metabolite level of ABA and increased transcript level accumulation of identified
eggplant putative ET biosynthetic genes in response to SFB feeding. Our findings
report that two major classes of defense metabolites of Solanaceae family, steroidal
alkaloids and phenolics abundantly present in eggplant fruit did not respond to
frugivory. Future studies focusing on the role played by these phytohormones and
their downstream targets can provide new insights about this crop-pest interaction
that can be exploited in pest management strategies.
