Function of jasmonate in response and tolerance of Arabidopsis to thrip feeding.

We analyzed the interaction between Arabidopsis and western flower thrips (Frankliniella occidentalis), which are one of the most serious insect pests of cultivated plants. We focused on the function of the immunity-related plant hormones jasmonate (JA), ethylene (ET) and salicylic acid (SA) in the plant's response to thrip feeding. Expression of the marker genes for each hormone response was induced by thrip feeding in wild-type (WT) plants. Further analyses in the hormone-related mutants coi1-1 (JA insensitive), ein2-1 and ein3-1 (ET insensitive) and eds16-1 (SA deficient) suggested the importance of these hormones in the plant response to feeding. Comparative transcriptome analyses suggested a strong relationship between thrip feeding and JA treatment, but not ET or SA treatment. The JA content of WT plants was significantly increased after thrip feeding. Moreover, coi1-1, but not ein2-1, showed lower feeding tolerance against thrips than the WT. Application of JA to WT plants before thrip feeding enhanced the plants' feeding tolerance. JA modulates several defense responses in cooperation with ET, but application of the ET precursor 1-aminocyclopropane-carboxylic acid had a marked negative effect on feeding tolerance. Our results indicate that JA plays an important role in Arabidopsis in terms of response to, and tolerance against, thrip feeding.