NITRIC OXIDE ACTIVATES PHOSPHOLIPID SIGNALLING IN PLANT CELLS

A. LAXALT, N. RAHO, A. TEN HAVE, A. DISTEFANO, C GARCIA-MATA, L. LANTERI AND L. LAMATTINA.

Rosario

Conferencia; Plant Biotechnology and economic regional development.; 2005

Nitric oxide (NO) and phosphatidic acid (PA) are two emerging molecules in plant stress signaling. Our objective is to elucidate if PA and NO signal transduction pathways are related. We wondered whether they act i) up or downstream of each other, ii) in parallel or iii) concerted (cross-talk). Since both NO and PA have been shown to be involved in plant defense responses during pathogen infections, we selected plant defense responses as a model system. Ultimately we will extend our research to ABA signalling during stomatal closure and auxin signalling during adventitous root formation. We observed both NO and PA production when tomato cells where treated with the fungal elicitor xylanase. Scavenging the produced NO resulted in a block of PA increase, indicating NO acts upstream of PA. Specific labeling experiments suggest that in xylanase treated cells, the NO-dependent PA is produced by phospholipase C (PLC). Similar results have recently been obtained with the elicitor chitotetraose and during the tomato- Cladosporium fulvum CF4-AVR4 interaction. Silencing experiments (VIGS) are underway in order to provide genetic evidence and to determine which member of the PLC gene family is required for a full plant-defense. Preliminary experiments directed at other signaling pathways in which NO and PA are involved have been performed. The obtained results indicate a relation between NO and PA in ABA induced stomatal closure as well as in auxin signaling during adventitious root formation. A model is proposed for the pathways of these signal molecules.   Supported by F. Antorchas, CONICET, ANPCyT, UNMdP, TWAS, and The Dutch Technology Foundation (STW).