Role of nitric oxide and phospholipase D in stomatal closure and drought stress.

AYELEN M. DISTÉFANO, CARLOS GARCÍA-MATA, LORENZO LAMATTINA AND ANA M. LAXALT.

Madryn

Congreso; SAIB; 2010

SAIB

Nitric oxide (NO) promotes stomatal closure and increases plant tolerance to drought stress. Previously, we have demonstrated the involvement of phospholipase D (PLD) and its product, the lipid second messenger phosphatidic acid (PA) in NO signalling during stomatal closure. PLDδ is one of the 12 Arabidopsis PLDs which has been involved in dehydration stress responses. However, the role of PLDδ in stomatal movement is unknown. In this work we used pldδ knock-out null mutants (pldδ) to show that PLDδ is required for NO, H2O2 and abscisic acid (ABA) induced stomatal closure. NO and H2O2 production upon ABA treatments in guard cells of pldδ plants was comparable to the levels in wild-type (wt). These data suggest that PLDδ is downstream of NO and H2O2 in ABA-induced stomatal closure. The transcript levels of RD29A were analyzed. pldδ plants showed higher RD29A transcript level compared to wt plants under normal growth conditions. Plants resistant to drought stress have higher level of RD29A transcript. In concordance, pldδ were resistant to drought as it is indicated by its high relative water content and its low ion leakage compared to wt plants. These results allow us to hypothesize a dual role of PLDδ during drought. At early drought stage PLDd participates of the signalling cascade leading to stomatal closure. However, at later stages PLDd participates in membrane degradation.