科研之友
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摘要
The stress-related phytohormones, salicylic acid (SA) and abscisic acid (ABA), and the three jasmonates, jasmonic acid (JA), cis-12-oxo-phytodienoic acid (cis-OPDA), and (+)-7-iso-jasmonoyl-L-isoleucine (JA-Ile), were investigated in phloem and xylem exudates of Cucurbita maxima. Phloem and xylem exudates were separately collected and analysed via liquid chromatography-mass spectrometry. We show direct evidence for all three jasmonates, ABA, and SA in both phloem and xylem exudates of C. maxima. JA and JA-Ile concentrations are higher in xylem (JA: c(xylem) approximate to 199.5 nM, c(phloem) approximate to 43.9 nM; JA-Ile: c(xylem) approximate to 7.9 nM, c(phloem) approximate to 1.6 nM), whereas ABA and SA concentrations are higher in phloem exudates (ABA: c(xylem) approximate to 37.1 nM, c(phloem) approximate to 142.6 nM; SA: c(xylem) approximate to 61.6 nM, c(phloem) approximate to 1319 nM). During bacteria-derived flagellin 22 (flg22)-triggered remote root-to-shoot signalling, phytohormone concentration changed rapidly both in phloem and xylem. The unequal distribution of phytohormones suggests that phloem and xylem have distinct roles in defence responses. Our data shed light on systemic phytohormone signalling and help explain how plants cope with environmental challenges by lateral exchange between phloem and xylem. Our analysis is a starting point for further investigations of how phytohormones contribute to phloem- and xylem-based defence signalling.
- 出版日期2014-3
