Abstract

TIJERINA-RAMIREZ, Niria et al. Osmotic stress effect on in vitro growth, pathogenicity and osmolyte production in Macrophomina phaseolina. Rev. Mex. Mic [online]. 2014, vol.39, pp.31-39. ISSN 0187-3180.

The fungus Macrophomina phaseolina causes charcoal rot in common bean (Phaseolus vulgaris) and although it tolerates osmotic stress the mechanisms of tolerance remain unknown. In this work under in vitro conditions it was determined the growth of six M. phaseolina isolates under variable NaCl (PDA with 0, 500 and 1000 mM); pathogenicity in four bean cultivare (Azufrado Tapatío, BAT 477, Pinto UI-114, SEQ12) growing; and the concentrations of glycerol, arabitol, D-fructose and D-glucose concentrations of each fungal isolate growing under 0,250, and 500 mM NaCl. NaCl (500mM) reduced M. phaseolina growth up 50%. Isolates from Rio Bravo, Tamaulipas were the most aggressive. The growth of M. phaseolina was negatively associated with osmolyte concentrations under no-NaCl conditions but positively with D-glucose concentration under 500 mM NaCl. Pathogenicity was negatively associated with osmolyte production. Osmotic stress induced de novo synthesis of osmolytes in M. phaseolina but reduced its aggressiveness in beans.

Keywords : Phaseolus vulgaris; HPLC analysis; arabitol; fructose; glycerol; glucose; charcoal rot.