The rapidly evolving associations among herbivore associated elicitor-induced phytohormones in Nicotiana.

In response to herbivore attack, plants perceive herbivore associated elicitors (HAE) and rapidly accumulate jasmonic acid (JA) and other phytohormones, which interact in complex ways, such as the crosstalk between JA and salicylic acid (SA). Although recent studies have shown that HAE-induced individual phytohormones can be highly specific among closely related species, it remains unclear how conserved and specific the relationships among HAE-induced phytohormones are. Here we analyzed the correlations among 4 different phytohormones, JA, JA-isoleucine (JA-Ile), SA, and abscisic acid (ABA) in 6 closely related Nicotiana species that were induced by 3 different HAEs. Our results showed that while no clear association between ABA and other phytohormones were found, the positive association between JA and JA-Ile is mostly conserved among closely related Nicotiana species. Interestingly, the association between JA and SA are highly variable and can be regulated by different HAEs.