NITRIC OXIDE AND SALT STRESS TOLERANCE IN WHEAT-AZOSPIRILLUM ASSOCIATION

ZAWOZNIK M.S.; GROPPA M.D.; BENAVIDES M.P.

Mar del Plata, Buenos Aires, Argentina

Congreso; XLIII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB).; 2007

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular (SAIB).

Salinity is one of the main constraints for expansion of cultivated areas and yield increases. There are reports showing higher performance under salt stress for wheat plants inoculated with the plant growth promoting rhizobacterium Azospirillum. Nitric oxide (NO) can be synthetized by Azospirillum and was involved as signaling molecule in plant salt stress adaptation. To detect the biochemical basis underlying this differential response, uninoculated and Azospirillum-inoculated wheat seeds were grown for 8 days in Hoagland nutrient solution alone (control) or containing 200 mM NaCl or 200 mM NaCl+100 ìM methylene blue (MB), a NO trapping agent. Plant height, chlorophyll content, fresh and dry weight of shoots and roots, and root morphology were assessed. Whereas chlorophyll contents did no vary, plant height and total plant biomass were significantly reduced upon salt exposure in both uninoculated and inoculated plants. This decrease, however, was less pronounced for inoculated plants. MB addition reverted this protective effect in inoculated plants. After salt treatment, roots were shorter (mainly in control plants), brownish and intensively branched. MB and salt co-treatment resulted in a significantly less brownishing. We conclude that NO is probably involved in Azospirillum-mediated alleviation of salt stress. Changes in phenolics/oxidized products should also be considered