NITRIC OXIDE AND PHOSPHATIDIC ACID SIGNALING DURING STOMATAL CLOSURE

DISTÉFANO A., GARCÍA-MATA C., LAMATTINA L., AND LAXALT A. M.

Pinamar, Argentina

Congreso; 10th Congress of PABMB, 41th Congress of SAIB and 20th Congress of SAN; 2005

Nitric oxide (NO) and Phosphatidic acid (PA) are two emerging molecules in plant signaling. It has been reported that both NO and PA are produced in guard cells in response to the plant hormone abscisic acid (ABA) during stomatal closure. In addition, the absence of any of this two signaling components, partially blocks ABA induction of stomatal closure. Since NO and PA signaling pathways share some common components (i.e, ion channels, calcium, etc), we decided to study the occurrence of a cross talk between both pathways in guard cells. PA is generated via phospholipase D (PLD) or via phospholipase C (PLC) in concerted action with diacylglycerol kinase (DGK). With that aim, we treated Vicia faba epidermal strips with the NO donor SNAP in presence or absence of specific inhibitors of PA synthesis enzymes. Results showed that primary alcohols (inhibitors of PA formation via PLD activation) and PLC inhibitors (neomycine and U73122) blocked NO induction of stomatal closure. We have also set up a system to measure in vivo phospholipid production in V.faba guard cells. An increase in PA content during NO-induced stomatal closure was observed. These results suggest that, in V. faba guard cells, PA is required for NO-dependent stomatal closure. Supported by ANPCyT, CONICET, Fund. Antorchas TWAS and UNMdP.