Сельскохозяйственная биология, 2011, № 3, с. 55-60.

УДК 633.31:581.557:631.461.5:575:575.224.46

USE OF SITE-DIRECTED MUTAGENESIS TO STUDY THE FUNCTIONS OF GENE SMb20332 IN THE NODULE BACTERIA Sinorhizobium meliloti

E.P. Chizhevskaya, O.P. Onishchuk, E.E. Andronov, B.V. Simarov

The mutant for gene SMb20332 derived from alfalfa nodule bacteria Sinorhizobium meliloti type strain 1021 has been constructed by the use of site-directed mutagenesis. This gene is located on the megaplasmid-2 and possibly encodes for arylsulfatease according to the results of complete genome sequence of strain 1021 S. meliloti. Symbiotic properties, salt resistance and growth on the diagnostic media for mutant ACH-5 have been tested. It was shown that arylsulfatases from nodule bacteria resemble the arylsulfatases from marine bacteria which are able for desulphation agaropectin. Mutation in gene SMb20332 does not effect significantly the salt resistance of strain 1021 S. meliloti as well as its efficiency and competitiveness in symbiosis with Medicago sativa (cv. Vega). It was firstly shown that mutation in the gene SMb20332 of strain 1021 S. meliloti causes the change of surface polysaccharides and loose of resistance to the herbicide 2M-4HM (inhibitor of the bacterial respiratory activity).

Keywords: Sinorhizobium meliloti, arylsulphatase, production of polysaccharides, herbicide resistance, salt tolerance, competitiveness, symbiotic effectiveness.