Phytohormone elicitation in maize by oral secretions of specialist Mythimna separata and generalist Spodoptera litura

Abstract

The innate machineries for regulation of plant defense responses against herbivores are strikingly based on stress response-associated phytohormones. However, the dynamics of the effects of distinct types of chewing herbivores’ oral secretion (OS) on phytohormone regulation are not well known. We explored the phytohormone regulation in maize leaves in response to OS from larvae of a specialist herbivore (Mythimna separata) and a generalist herbivore (Spodoptera litura). In response to mechanical damage with application of those OSs, maize leaves rapidly upregulated the endogenous levels of oxylipins and abscisic acid (ABA) in quantitatively similar manners. Moreover, it appeared that bacteria in OS were responsible for the coordination of ABA levels. Our findings suggest that, during predation by the specialist and generalist lepidopteran herbivores, their OSs similarly upregulate phytohormone levels and the presence of their oral bacterial community makes a minor impact on maize defense responses.

Keywords

• bacteria
• herbivore
• maize
• oral secretion
• phytohormone