Identification of new genes of nodule bacteria Sinorhizobium meliloti involved in the control of efficiency of symbiosis with alfalfa Medicago sativa

Abstract

Using a Tn5 mutagenesis in a Sinorhizobium meliloti strain CXM 1-105, we obtained three mutants with increased symbiotic efficiency with alfalfa. Our study demonstrated Tn5 insertions labeled two chromosome genes encoding 5-adenosylhomocysteine methylthioadenosine deaminase (mutant T4) and a protein belonging to the GntR family of transcription regulators (mutant M3) and a thiamine biosynthetic gene thiC, localized at megaplasmide 2 (mutant T795). Mutant T795 along with high symbiotic efficiency exhibited a reduced ability to compete for nodulation with the parent strain CXM1-105.