Differential role of PLDδ in early or late stages of drought stress.

AYELEN M. DISTÉFANO, MATIAS VALIÑAS, LORENZO LAMATTINA, CARLOS GARCÍA-MATA, ANA M. LAXALT AND ARJEN TEN HAVE.

La Plata

Congreso; SAFV; 2010

Phospholipase D (PLD) is a major family of lipid-hydrolyzing enzymes. Arabidopsis has 12 isozymes, from which PLDδ has been implicated in drought response. We recently showed that PLD activation is required for NO-induced stomatal closure in Vicia faba. We used Arabidopsis pldδ knock-out null mutants (pldδ) to show that PLDδ is downstream of NO and ABA-induced stomatal closure. Since stomatal closure is a key plant mechanism for reducing the water loss during drought, the aim of this work is to analyze the tolerance to drought of pldδ plants. Thus, wild-type (wt) and pldδ plants watered for three days with water, ABA or GSNO (NO donor) were subjected to drought by stopping irrigation for 12 days. Wild-type non-treated plants displayed a wilting phenotype and have reduced relative leaf water content (RWC) compared to GSNO or ABA treated plants. Interestingly, pldδ plants were tolerant to drought since they did not showed the wilting phenotype and had almost the same RWC than GSNO or ABA-treated wt plants. Because drought stress led to a massive breakdown of membrane lipids we measured the ion leakage. pldδ plants have less ion leakage than wt plants. Thus, drought tolerance of pldδ plants could be due to membrane stability. In concordance, AtPLDδ-overexpressing tobacco plants displayed an increased susceptibility to drought respect to control ones. These results allow us to hypothesize a dual role of PLDδ during drought: an early activation would induce stomatal closure, and at later stages would induce cellular damage. Futures studies will be done to corroborate this hypothesis.