Nodulation and Nitrogen Fixation Efficacy of Rhizobium fredii with Phaseolus vulgaris Genotypes.
Phaseolus plant introduction (PI) genotypes (consisting of 684 P. vulgaris, 26 P. acutifolius, 39 P. lunatus, and 5 P. coccineus accessions) were evaluated for their ability to form effective symbioses with strains of six slow-growing (Bradyrhizobium) and four fast-growing (Rhizobium fredii) soybean rhizobia. Of the 684 P. vulgaris genotypes examined, three PIs were found to form effective nitrogen-fixing symbioses with the R. fredii strains. While none of the Bradyrhizobium strains nodulated any of the genotypes tested, some produced large numbers of undifferentiated root proliferations (hypertrophies). A symbiotic plasmid-cured R. fredii strain failed to nodulate the P. vulgaris PIs and cultivars, suggesting that P. vulgaris host range genes are Sym plasmid borne in the fast-growing soybean rhizobia.
Sadowsky
M J
MJ
Nitrogen Fixation and Soybean Genetics Laboratory, Agricultural Research Service, U.S. Department of Agriculture, Building 011, HH19, BARC-West, Beltsville, Maryland 20705.
Cregan
P B
PB
Keyser
H H
HH