Differential role of PLD in early or late stages of drought stress

DISTÉFANO, A.; VALIÑAS, M.; LAMATTINA L; GARCÍA-MATA, C,; LAXALT, A. M.; TEN HAVE, A

La Plata

Congreso; XXVIII Reunión Argentina de Fisiología Vegetal; 2010

Sociedad Argentina de Fsiología Vegetal (SAFV)

st1:*{behavior:url(#ieooui) }st2:*{behavior:url(#ieooui) } Phospholipase D (PLD) is a major family of lipid-hydrolyzing enzymes. Arabidopsis has 12 isozymes, from which PLDd 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 pldä knock-out null mutants (pldä) to show that PLDä 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 pldä plants. Thus, wild-type (wt) and pldä 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, pldä 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. pldä plants have less ion leakage than wt plants. Thus, drought tolerance of pldä plants could be due to membrane stability. In concordance, AtPLDä-overexpressing tobacco plants displayed an increased susceptibility to drought respect to control ones. These results allow us to hypothesize a dual role of PLDä 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.