A role for phospholipase D in nitric oxide induced stomatal closure

DISTÉFANO AYELEN; GARCÍA-MATA CARLOS; LAMATTINA LORENZO; LAXALT ANA MARÍA

Aguas de Lindoia, Sao Pablo, Brazil

Congreso; XXXVIII Annual Meeting of Brazilian Biochemistry and Molecular Biology Society-SBBq-Conesul para Jovem Cientista; 2009

Plants regulate the uptake of carbon dioxide and water loss through pores, called stomata, located in the epidermis of the aerial parts of the plants. Stomatal closure is an essential event for plant survival upon drought stress. The closure is regulated by a complex network of signalling events involving numerous intermediates, among them nitric oxide (NO). Previous studies have shown that NO modulates cytosolic calcium concentration and the activation of plasma membrane ion channels. Our results showed that NO also induces stomatal closure via activation of phospholipase D (PLD) with the consequent production of phosphatidic acid (PA). Multiple PLD isozymes exist. Arabidopsis has 12 with distinguishable biochemical and regulatory properties, and also with little functional redundancy. Two isoforms (PLDalpha1 and delta) had been related to drought response. Our current goal is to determine whether PLDalpha1 and PLDdelta are required for NO induced stomatal closure. As a measure of stomatal closure we evaluate the leaf loss of fresh weight (LFW), since LFW is largely determined by stomatal conductance. NO treated wild type plants shows less LFW than non-treated plants, reflecting the fact that NO induces stomatal closure. In pld1 plants, NO treatment partially avoided the reduction of LFW; but it has no effects on LFW of plddelta and pldalpha1-plddelta mutants. These results were corroborated by direct microscopic stomata observation in epidermal peels of NO-treated wild type and mutants plants. This indicates that during stomatal closure NO could be activating PA accumulation via PLDalpha and partially via PLDalpha1. Futures studies will be done to measure NO induces gene transcription in PLD mutants.