Abstract
To investigate the putative crosstalk between JA and ABA in Solanum lycopersicum plants in response to drought, suppressor of prosystemin-mediated responses2 (spr2, JA-deficient) and flacca (flc, ABA-deficient) mutants together with the naphthalene/salicylate hydroxylase (NahG) transgenic (SA-deficient) line were used. Hormone profiling and gene expression of key enzymes in ABA, JA and SA biosynthesis were analyzed during early stages of drought. ABA accumulation was comparable in spr2 and wild type (WT) plants whereas expression of 9-cis-epoxycarotenoid dioxygenase 1 (NCED1) and NCED2 was different, implying a compensation mechanism between NCED genes and an organ-specific regulation of NCED1 expression. JA levels and 12-oxo-phytodienoic acid reductase 3 (OPR3) expression in flc plants suggest that ABA regulates the induction of the OPR3 gene in roots. By contrast, ABA treatment to flc plants leads to a reduction of JA and SA contents. Furthermore, different pattern of SA accumulation (and expression of isochorismate synthase and phenylalanine ammonia lyase 1) was observed between WT seedlings and mutants, suggesting that SA plays an important role on the early response of tomato plants to drought and also that JA and ABA modulate its biosynthesis. Finally, hormone profiling in spr2 and NahG plants indicate a crosstalk between JA and SA that could enhance tolerance of tomato to water stress.
Highlights
Drought is by far the most important environmental constrain in agriculture and every year the number of economic losses due to water constraints increases (Vicente-Serrano, 2007)
Stress conditions caused an important loss of leaf water in spr2 and CSL plants, and relative water content (RWC) followed a similar pattern in both genotypes (Figure S2A)
Our data demonstrate that the expression of key genes for the biosynthesis of these three hormones is induced by drought and that regulation of jasmonic acid (JA) and abscisic acid (ABA) levels differs in roots and leaves
Summary
Drought is by far the most important environmental constrain in agriculture and every year the number of economic losses due to water constraints increases (Vicente-Serrano, 2007). This problem has been aggravated in the last decade by global climate changes. The role of phytohormones have been described considering individual signaling pathways but this approach. Hormonal Interactions in Tomato does not address the spatiotemporal specificity, considered central to fine-tune hormone signaling. The study of hormone profiling during early stages of water stress conditions in different mutant backgrounds could help to distinguish common from specific responses
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