AZOSPIRILLUM BRASILENSE PRODUCES ABA IN CHEMICALLY-DEFINED CULTURE MEDIA

COHEN AC; BOTTINI R; PICCOLI P

Puerto Vallarta, México

Congreso; IPGSA Conference; 2007

Azospirillum sp. are plant growth promoting bacteria (PGPB) that increase grain yield in cereals and other species via growth promotion and/or stress alleviation. The PGPB beneficial effects have been partially attributed to bacterial production of plant hormones, especially ?growth promoters? like auxins, gibberellins and cytokinins. This work reports the characterization of the stress-like plant hormone abscisic acid (ABA) by GC-EIMS in cultures of A. brasilense after 120 h of incubation in chemically-defined media. The addition of 100 mM NaCl in the culture media reduced bacterial growth assessed as OD540 (total biomass) and CFU ml-1 (cells alive) by 1/3. However, under such stressful conditions Azospirillum improved three-folds the ABA production (73 versus 235 ng.mL-1 of culture medium). Since saline soils are one of the most problematic aspects in nowadays world agriculture, PGPB with improved capacity of ABA production may help in plant-stress alleviation.