Soybean (Glycine max) genotype–mediated variation in the symbiotic performance of Rhizobium

Abstract

Legume–rhizobium interaction is the result of molecular dialogue involving a succession of events on the perception of signal molecules produced and secreted by both partners. Soybean (Glycine max L.) is known to be nodulated by two different genera, Bradyrhizobium (slow growing rhizobia) and Sinorhizobium (fast growing) species. The present investigation is an attempt to understand the host genotypic effect on the fast and slow growing root nodulating bacteria of soybean which impacts the biological nitrogen fixation and would lead to the selection of best cultivar-strain compatible interaction. Five soybean genotypes of North Plain Zone, viz. DS 12-13, DS 9712, DS 2705, SL 979, SL 982 were evaluated for their symbiotic potential with two slow (KAS-1, MTCC10753) and two fast growing root nodulating bacteria (DS-1, LSR-8). Genotype DS12-13 formed significant number of nodules with KAS-1 with LS mean of 17.3. Genotype DS 2705 was poorly nodulated by the four strains. Among the strains, slow growing KAS-1 and fast growing DS-1 strains were effective across the genotypes. There was significant increase in the specific acetylene reducing activity of these strains 71.1 and 72.6 nmoles of C2H4 produced/mg/ndw respectively. These strains conformed to the biochemical identification by failing to grow on citrate, glucose peptone agar and Hoffer's alkaline media.