NITRIC OXIDE AND PHOSPHATIDIC ACID CROSSTALK

ANA M. LAXALT, AYELEN M. DISTÉFANO, DENISE SCUFFI, JUAN MARTIN D?AMBROSIO, GABRIELA GONORAZKY, LORENZO LAMATTINA, CARLOS GARCÍA-MATA

Galveston

Congreso; Gordon Research Conferene on Plant Lipids; 2013

Nitric Oxide (NO) is an important redox based regulator of cell physiology and is involved in many signalling processes in plants. The precise mechanism of how NO interacts with or activates different targets is still poorly understood. NO can activate signalling pathways that implicate cGMP, cADPR, Ca2+, ion channels and protein kinases such as MAPKs and CDPKs. The polar lipid phosphatidic acid (PA) is another molecule involved in plant signalling. Two enzymatic pathways produce PA, phospholipase D (PLD) and phospholipase C (PLC) in concerted action with diacylglycerol kinase (DGK). PA affects ion channels, NADPH oxidase and protein kinases and phosphatases. NO and PA have been independently regarded as general and multifunctional signalling molecules in plants. Since both share common effectors we hypothesized NO and PA participate in the same signalling pathway. Results obtained in our laboratory revealed that NO can induce PA formation during plant-defense responses and stomatal closure. NO is involved 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 via two enzymatic pathways, PLD and PLC/DGK (van der Luit et al., 2000). We have demonstrated that the fungal elicitor xylanase requires NO to rapidly activate the PLC pathway and downstream defence responses in tomato cell suspensions and that S-nitrosylation is the NO post-translational modification involved in the PLC activation (Laxalt et al., 2007; Lanteri et al., 2011). We are currently silencing tomato PLCs in order to elucidate which one is the PLCs are activated by NO in xylanase induced PLC pathway. ii) NO reduces transpirational water loss by inducing stomatal closure (Garcia-Mata and Lamattina 2001). PLC and PLD activities are required for NO-induced PA formation and stomatal closure in Vicia faba guard cells (Distéfano et al., 2008). NO increases PLD activity that is required for NO-induced stomatal closure. Arabidopsis has 12 PLD genes and only two AtPLDs isoenzymes, PLDα1 and PLDδ, have been related to drought and dehydration stress. Recent evidences indicate that PLDα1 is upstream of NO production. However, we showed that PLD activation is downstream NO. Thus we hypothesized that PLDd could be activated by NO. PLDδ mRNA levels increases in ABA-treated guard cells. PLDδ knock-out plants (pldδ) failed to close the stomata in response to NO. ABA signalling in guard cells involves H2O2 and NO production. pldδ guard cells produced similar NO and H2O2 levels as the wild type in response to ABA. However, ABA- or H2O2-induced stomatal closure was impaired in pldδ plants (Distéfano et al., 2012). Unexpectedly, pldδ plants were more tolerant to drought. These data indicates that PLDδ is downstream of NO and H2O2 in ABA-induced stomatal closure and participates in drought stress. We are currently studying how does NO regulates PLDd activity. Supported by CONICET, ANPCyT and UNMdP. * Please consider this abstract for an oral presentation in Lipid Mediators and Signaling section References Distéfano AM, García-Mata C, Lamattina L, Laxalt AM. 2008. Nitric oxide-induced phosphatidic acid accumulation: a role for phospholipases C and D in stomatal closure. Plant Cell Environ 31: 187-194. Distéfano AM, Scuffi D, García-Mata C, Lamattina L, Laxalt AM. Phospholipase Dδ is involved in nitric oxide-induced stomatal closure. Planta. 2012 García-Mata C, Lamattina L. 2001. Nitric oxide induces stomatal closure and enhances the adaptive plant responses against drought stress. Plant Physiol 126: 1196-1204. Lanteri ML, Laxalt AM, Lamattina L. 2008. Nitric oxide triggers phosphatidic acid accumulation via phospholipase D during auxin-induced adventitious root formation in cucumber. Plant Physiol 147: 188-198. Laxalt AM, Raho N, Ten Have A, Lamattina L. 2007. Nitric oxide is critical for inducing phosphatidic acid accumulation in xylanase-elicited tomato cells. J Biol Chem 282: 21160-21168. van der Luit AH, Piatti T, van Doorn A, Musgrave A, Felix G, Boller T, Munnik T. 2000. Elicitation of suspension-cultured tomato cells triggers the formation of phosphatidic acid and diacylglycerol pyrophosphate. Plant Physiol 123: 1507-1516.