ROLE OF GLUTATHIONE IN THE GROWTH OF BRADYRHIZOBIUM SP (PEANUT MICROSYMBIONT) UNDER DIFFERENT ENVIRONMENTAL STRESSES AND IN SYMBIOSIS WITH HOST PLANT

SOBREVALS, L.; MULLER,P.; FABRA,A.; CASTRO,S.

CANADIAN JOURNAL OF MICROBIOLOGY

Año: 2006 p. 606 - 616

0008-4166

Glutathione (GSH) plays an important role in the defence of microorganisms and plants against different environmental stresses. To determine the role of GSH under different stresses, such as acid pH, saline shock and oxidative shock, a GSH-deficient mutant (Bradyrhizobium sp 6144-S7Z) was obtained by disruption of the gshA gene, which encodes the enzyme -glutamylcysteine synthetase. Growth of the mutant strain was significantly reduced in liquid minimal saline medium, and the GSH content was very low, about 4% of the wild type level.The defect caused by disruption of the gshA gene in the growth of mutant strain, cannot be reversed by the addition of GSH (up to 100 umol/L) to the liquid minimal saline medium, and the endogenous GSH level was approximately the same as that observed without the addition of GSH. In contrast, the wild-type strain increased the GSH content under these conditions. However, the growth of mutant strain in a rich medium increased, suggesting that at least some but not all of the functions of GSH could be provided by peptides and (or) aminoacids. The symbiotic properties of the mutant were similar to those found in the wild-type strain, indicating that the mutation does not affect the ability of the mutant to form effective nodules.