LIPIDS: New messengers of Nitric Oxide in plant defense

GABRIELA GONORAZKY, JUAN MARTIN DAMBROSIO, LORENZO LAMATTINA AND ANA M. LAXALT

Conferencia; Society fro Free Radical Biology and Medicine; 2013

Nitric oxide (NO) is a biologically relevant radical involved in signalling processes in plants. Its lipophilic character exposes membrane proteins, lipoproteins and lipids to NO chemistry. The polar lipid phosphatidic acid (PA) is another molecule involved in plant signalling. Two enzymatic pathways generate PA, phospholipase D (PLD) and phospholipase C (PLC) in concerted action with diacylglycerol kinase (DGK). Since NO and PA share common effectors we hypothesized that they participate in the same signalling pathway. NO participates in the plant defense response of a growing list of plant-pathogen interactions. Xylanase is a fungal elicitor that activates a rapid PA production in tomato cells. We have demonstrated that xylanase requires NO to rapidly activate the PLC pathway and downstream defense responses in tomato cell suspensions and experimental evidence suggests that NO-dependent S-nitrosylation modulates PLC activation. The expression profile of the SlPLC gene family shows that its members are differentially expressed in tomato cell suspensions treated with xylanase. Currently, silencing of tomato PLCs is used to elucidate the PLC isoforms that are regulated by NO. In animals, NO-derived reactive nitrogen species formed during inflammation react with unsaturated fatty acids yielding nitro-fatty acids (NO2-FAs), representing novel lipid mediators derived form NO sinaling. Preliminary results show that NO2-FAs are also produced in xylanase-treated tomato cells, they induce plant-defense responses thus introducing a novel NO-derived lipid player into the plant-pathogen interactions Supported by CONICET, ANPCyT and UNMdP.