NITRIC OXIDE AND PHOSPHATIDIC ACID CROSSTALK IN (A)BIOTIC STRESS

GONNORAZKY GABRIELA; DISTÉFANO AYELEN MARIANA; GUZZO CARLA; SCUFFI DENISE; ABD-EL-HALIEM A,; JOOSTEN M,; RAMIREZ LEONOR; VALIÑAS MATIAS ; TEN HAVE ARJEN; DAMBROSSIO JUAN MARTÍN; LAMATTINA LORENZO; GARCÍA-MATA CARLOS; LAXALT ANA MARÍA

Galvesston, Texasa, USA

Congreso; Gordon Research Conferences, Plant Lipids; 2013

Gordon Research Conferences

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 pld 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