Nitric oxide and ethylene involvement in drought tolerance/susceptibility in oat

Trabajo presentado en la 6th Plant Nitric Oxide International Meeting, celebrada en Granada del 14 al 16 de septiembre de 2016.Drought is one of the major threats to food security but improving drought tolerance in crops is a complex task. This is in part because drought tolerance responses are extremely complex and involve a wide range of processes and intricate signaling events. In a previous work we observed that transgenic barley lines overexpressing the barley non-symbiotic hemoglobin gene HvHb1 which oxidizes NOto N03- were more resistant to drought. We also observed that drought resistance in the transgenic barleys was mediated by polyamine pathways. In this work we explored whether inherent reduction of NO was a natural feature of drought resistance in oat and that it could be related with changes in polyamine and ethylene, which share part of the polyamine biosynthesis pathway, during the drought response. We monitored endogenous nitric oxide (NO) production in the oat cultivars Patones and Flega, characterized as drought tolerant and susceptible, respectively, and data suggested lesser production in the resistant genotype at increasing drought stress. We are now performing gene expression analysis through RT-PCR to determine the expression of specific genes for polyamine and ethylene pathway, i.e. arginine decarboxylase (ADC), and 1-aminocyclopropane-1- carboxylate oxidase (ACO), respectively, and also for genes that are common nodes for polyamine and ethylene biosynthesis: i.e. methionine adenosyltransferase (MAT), Sadenosylmethionine decarboxylase (AdoMetDC) and 1-aminocyclopropane-1-carboxylate [ACC] synthase (ACS), which catalyzes the first committed step in ethylene biosynthesis diverging from polyamine pathway. Preliminary results showed an increase of more than 20 fold of ACO gene expression in cultivar Flega under drought compared with Patones suggesting an increase of ethylene biosynthesis linked with drought susceptibility. Further work will include the monitoring of in vivo ethylene production under well-watered and drought conditions.N