(E)-β-Farnesene Protects Rice from Rice Striped Stem Borer Attack by Inhibiting Its Beneficial Gut Microbes.

Area of Science:

• Plant-insect interactions
• Microbial ecology
• Biochemistry

Background:

• Herbivore gut microbes are crucial for development, nutrition, and survival.
• Plant defenses can target these microbes, but this is understudied in rice.
• Rice striped stem borers (SSB) are significant agricultural pests.

Purpose of the Study:

• To investigate the role of rice terpene synthase gene Os04g0341500 in plant defense against SSB.
• To determine if the synthesized compound (E)-β-farnesene (Eβf) affects SSB development and gut microbiota.
• To elucidate the mechanism by which Eβf impacts SSB.

Main Methods:

• Identified and characterized the rice terpene synthase gene Os04g0341500.
• Assessed the effect of Eβf on SSB larval development and survival using artificial diets.
• Analyzed changes in SSB gut microbial communities using high-throughput amplicon sequencing.
• Performed in vitro experiments to confirm the antimicrobial activity of Eβf against gut microbes.

Main Results:

• The rice gene Os04g0341500 was induced by SSB feeding and synthesized (E)-β-farnesene (Eβf).
• Eβf significantly impaired SSB larval development and survival.
• SSB fed Eβf showed a decrease in beneficial gut microbes compared to controls.
• Eβf directly inhibited the growth of SSB gut microbes in vitro.

Conclusions:

• Rice plants can defend themselves by producing Eβf, which disrupts the gut microbiota of SSB.
• The reduction in beneficial gut microbes due to Eβf negatively impacts SSB larval development and survival.
• This study highlights a novel mechanism of plant defense involving the manipulation of insect gut microbial communities.