Different expression profiles of jasmonic acid and salicylic acid inducible genes in the tomato plant against herbivores with various feeding modes

We compared the expression profiles of jasmonic acid (JA)-inducible genes (Pin2 and LapA1) and salicylic acid (SA)-inducible genes (PRb-1b and GluB) in the tomato (Solanum lycopersicum cv. Micro-Tom) against herbivores using differing feeding modes: the leaf-chewing larvae of the insects Spodoptera litura and S. exigua; the western flower thrips (Frankliniella occidentalis) and the two-spotted spider mite (Tetranychus urticae) as cell-content feeders; and the leaf miner fly (Liriomyza sativae). Feeding by larvae of both S. litura and S. exigua chiefly activated JA-inducible genes, similar to the response to wound stimuli. Feeding by the thrips F. occidentalis also activated JA-inducible genes, as previously reported in Arabidopsis. Feeding by the spider mite T. urticae activated a JA-inducible LapA1 gene but did not activate a JA-inducible Pin2 gene and additionally activated SA-inducible genes, which were accompanied by the accumulation of SA. This may be a strain that represses induction of the JA signaling pathway. One day after oviposition by the leaf miner fly, L. sativae, JA-inducible genes were activated. However, after the L. sativae larvae hatched and began eating within the leaf tissues, JA-inducible gene expression decreased and SA-inducible gene expression increased. Activation of SA-inducible genes (PRb-1b and GluB) by L. sativae larval feeding seems to suppress JA-mediated plant defense but appears to be unrelated to SA accumulation.