FIG. 4.

Amplification products of nested PCR using IGS-targeted primers specific for Bradyrhizobium sp. strain IRBG271 (A) or Rhizobium sp. strain IRBG74 (B) in pure culture (lanes 1) or in the presence of a mixture of related bacteria (lanes 2 through 12). DNA pools of numerous reference strains (Table 1) of Bradyrhizobium spp. (A) or Rhizobium, Mesorhizobium, and Sinorhizobium (B) were used as templates. The specific IGS-targeted primers R3ssf-R3ssr (A) and R2ssf-R2ssr (B) were used in the second reaction mixture; 5 μl of the amplification product was loaded on a 1.1% agarose gel. The products were approximately 450 (A) or 1,000 (B) bp in size. M, size marker (λ DNA digested with PstI). (A) Lanes: 1, strain IRBG271; 2, strain pool A plus IRBG271; 3, strain pool A; 4, strain pool B; 5, strain pool C plus IRBG271; 6, strain pool C; 7, strain pool D plus IRBG271; 8, strain pool D; 9, strain pool E plus IRBG271; 10, strain pool E; 11, strain pool F plus IRBG271; 12, strain pool F. (B) Lanes: 1, IRBG74; 2, strain pool G plus IRBG74; 3, strain pool G; 4, strain pool H plus IRBG74; 5, strain pool H; 6, strain pool I plus IRBG74; 7, strain pool I; 8, strain pool J plus IRBG74; 9, strain pool J; 10, strain pool K plus IRBG74; 11, strain pool K.