Plant-to-plant defence induction in cotton is mediated by delayed release of volatiles upon herbivory

Data and R scripts for statistical analyses for the article "Plant-to-plant defence induction in cotton is mediated by delayed release of volatiles upon herbivory".

By: Luca Grandi, Wenfeng Ye, Mary V. Clancy, Armelle Vallat, Gaétan Glauser, Luis Abdala-Roberts, Thierry Brevault, Betty Benrey, Ted C.J. Turlings, Carlos Bustos-Segura

Summary:

·      Caterpillar feeding immediately triggers the release of volatile compounds stored in the leaves of cotton plants. Additionally, after one day of herbivory, the leaves release other newly synthesised volatiles. We investigated whether these volatiles affect chemical defences in neighbouring plants and whether such temporal shifts in emissions matter for signalling between plants. 

·     Undamaged receiver plants were exposed to volatiles from plants infested with Spodoptera caterpillars. For receiver plants, we measured changes in defence-related traits such as volatile emissions, secondary metabolites, phytohormones, gene expression, and caterpillar feeding preference. Then, we compared the effects of volatiles emitted prior to and after 24 h of damage on neighbouring plant defences. 

·      Genes that were upregulated in receiver plants following exposure to volatiles from damaged plants were the same as those activated directly by herbivory on a plant. Only volatiles emitted after 24 h of damage, including newly produced volatiles, were found to increase phytohormone levels, upregulate defence genes, and enhance resistance to caterpillars.

·      These results indicate that the defence induction by volatiles is a specific response to de novo synthesised volatiles, suggesting that these compounds are honest signals of herbivore attack. These findings point to an adaptive origin of airborne signalling between plants.