Volatile DMNT directly protects plants against <i>Plutella xylostella</i> by disrupting the peritrophic matrix barrier in insect midgut.

Abstract

Insect pests negatively affect crop quality and yield; identifying new methods to protect crops against insects therefore has important agricultural applications. Our analysis of transgenic <i>Arabidopsis thaliana</i> plants showed that overexpression of <i>pentacyclic triterpene synthase 1</i>, encoding the key biosynthetic enzyme for the natural plant product (3E)-4,8-dimethyl-1,3,7-nonatriene (DMNT), led to a significant resistance against a major insect pest, <i>Plutella xylostella</i>. DMNT treatment severely damaged the peritrophic matrix (PM), a physical barrier isolating food and pathogens from the midgut wall cells. DMNT repressed the expression of <i>PxMucin</i> in midgut cells, and knocking down <i>PxMucin</i> resulted in PM rupture and <i>P. xylostella</i> death. A 16S RNA survey revealed that DMNT significantly disrupted midgut microbiota populations and that midgut microbes were essential for DMNT-induced killing. Therefore, we propose that the midgut microbiota assists DMNT in killing <i>P. xylostella</i>. These findings may provide a novel approach for plant protection against <i>P. xylostella</i>.