Root-secreted (-)-loliolide mediates chemical defense in rice and wheat against pests

Plant chemical defense can be elicited by signaling chemicals. As yet, the elicitation is mainly known from volatile aboveground signals. Root-secreted belowground signals and their underlying mechanisms are largely unknown. This study examined a root-secreted signaling (-)-loliolide to trigger chemical defense in rice and wheat against pests by means of cocultivation and incubation experiments.

Wild-type Arabidopsis (WT) and its root exudates with (-)-loliolide induced the production of defensive metabolites of rice and wheat and reduced the performance of weeds, pathogens and herbivores, while a carotenoid-deficient mutant (szl1-1) and its root exudates without (-)-loliolide had no similar effects. However, the induction and reduction occurred in the szl1-1 root exudates by (-)-loliolide supplementation with the level equal to that of WT. RNA-sequencing analysis revealed a significant change in the transcript level of defense-related genes in rice exposure to (-)-loliolide. Furthermore, (-)-loliolide enhanced rice resistance against Rhizoctonia solani through changing reactive oxygen species (ROS) system, and mediating jasmonic acid, salicylic acid and abscisic acid biosynthesis.

Root-secreted signaling (-)-loliolide can trigger chemical defense in rice and wheat against their pests. Such perception-dependent chemical defenses provide an intriguing possibility for ecological pest management to increase crop productivity and sustainability. © 2024 Society of Chemical Industry.