LIPID METABOLISM IN BARLEY ROOTS (Hordeum vulgare) GERMINATED UNDER SALT AND OSMOTIC STRESS

MV MERINGER; JI USORACH; EE MACHADO; GE RACAGNI

San Juan

Congreso; XVIII Reunion Anual de la Sociedad de Biologia de Cordoba; 2011

Salt stress is one of the abiotic factors that limit normal plant development and activates signaling processes. Salinity causes both osmotic and ionic effects; the osmotic is triggered by excess salt in the soil, while the ion is due to excessive salt accumulation in the cells. Phospholipids are membrane components that play important roles as mediators in signal transduction. Therefore it was necessary to determine changes at the lipid signals in roots of barley germinated 4 days under salt stress (100 mM NaCl) and osmotic stress (200 mM mannitol). Salt stress increased the levels of phosphatidic acid (PA), while mannitol caused not only increased levels of PA, it also increased the levels of diacylglycerol pyrophosphate (DGPP) due to the activity DAG-k and PA-k, respectively. DGPP phosphatase activity remained unchanged, while the PA phosphatase activity was decreased in both types of stress. PLD activity also increased in treatments with NaCl and mannitol. On this basis, one could say that abiotic stress (salt and osmotic) not only increased the levels of PA in roots by increasing the activity DAG-k but it would also generate a pool of PA from PLD activity. On the other hand, PI3-k and PI4-k activities were affected both in response to salt and osmotic stress, PI3-k would also be involved in the production of active oxygen species (EAOs) via the NADHP-oxidase complex in response to stress by mannitol but not salt stress. Otherwise, increases in PI4P could be mediated by increased levels of salicylic acid (SA). In relation to the results obtained, it is suggested an interconnetion between signaling pathways, which are mediated by phospholipids triggered under stress conditions in barley roots.