Enhancement of root hydraulic conductivity by methyl jasmonate and the role of calcium and abscisic acid in this process

Abstract

The role of jasmonic acid in the induction of stomatal closure is well known. However, its role in regulating root hydraulic conductivity (L) has not yet been explored. The objectives of the present research were to evaluate how JA regulates L and how calcium and abscisic acid (ABA) could be involved in such regulation. We found that exogenous methyl jasmonate (MeJA) increased L of Phaseolus vulgaris, Solanum lycopersicum and Arabidopsis thaliana roots. Tomato plants defective in JA biosynthesis had lower values of L than wildtype plants, and that L was restored by addition of MeJA. The increase of L by MeJA was accompanied by an increase of the phosphorylation state of the aquaporin PIP2. We observed that MeJA addition increased the concentration of cytosolic calcium and that calcium channel blockers inhibited the rise of L caused by MeJA. Treatment with fluoridone, an inhibitor of ABA biosynthesis, partially inhibited the increase of L caused by MeJA, and tomato plants defective in ABA biosynthesis increased their L after application of MeJA. It is concluded that JA enhances L and that this enhancement is linked to calcium and ABA dependent and independent signalling pathways.

Arbuscular mycorrhizal symbiosis and methyl jasmonate avoid the inhibition of root hydraulic conductivity caused by drought

“…An antibody against phosphorylated PIP2 at the C-terminal end of PvPIP2;1 (CAIKALG{pSER}FRSNA) was also used. A previous check for the specificity of each antibody (Sanchez-Romera et al 2014) showed that each antibody was very specific to its target protein, phosphorylated or not. These antibodies were developed in rat (anti-PIP1) and in rabbits (anti-PIP2 and antiphosphorylated PIP2) by Abyntek Company (Bilbao, Spain).…”

ABA-regulation of root hydraulic conductivity and aquaporin gene- expression is crucial to the plant shoot rise caused by rhizosphere humic acids

“…The interest of using this methodology is that the regulation of cell to cell water transport involves the activity of PIPs (Maurel et al, 2008), which was also evaluated in our experiments. Previous studies showed the good concordance between Lp r measured by the free exudation method and that measured by the pressure chamber method (Sánchez-Romera et al, 2014). Plant shoots were excised in their growing hydroponic medium.…”

“…6). Numerous studies have shown the relevant role of root ABA in regulating Lp r (Hose et al, 2000;Thompson et al, 2007;Tardieu et al, 2010;Sánchez-Romera et al, 2014) and the expression of genes encoding some families of PIP proteins as well (Beaudette et al, 2007;Mahdieh and Mostajeran, 2009). Assuming the limitations linked to all pharmacological approaches because of the possibility of side effects of inhibitors and precursors on unwanted biochemical pathways ("Materials and Methods"), our experiments indicated that the SHA-mediated increase in Lp r is ABA dependent, because the application of Fld, a specific inhibitor of ABA biosynthesis in root and shoot, abolished SHA action on Lp r .…”

“…The concentration of Fld was based on experiments reported by Sánchez-Romera et al (2014), and dose-response experiments were carried out before conducting final experiments. We analyzed shoot growth, Lp r , ABA concentration in roots, and PIP gene expression in roots.…”

Jasmonic acid interacts with abscisic acid to regulate plant responses to water stress conditions

“…Moreover, exogenous treatment with jasmonates increased ABA levels in different Species both under control conditions or exposed to drought. 10,11 The reciprocal treatment with exogenous ABA had no significant effect on endogenous JA levels in citrus plants. 11 In order to understand the effect of JA on plant responses to desiccation, proline accumulation after dehydration was analyzed in different Arabidopsis seedlings: a line defective in JA-Ile biosynthesis (jar1-1), 2 JA insensitive lines (jai1 and coi1-16), and an ABA insensitive line (abi2).…”