Molecular Marker Characterization of a Supernodulating Soybean Mutant, SS2-2

Symbiotic nodulation on root in legumes is regulated not only by environmental factors but also by autoregulation. Among soybean mutants deficient autoregulation, SS2-2, supernodulating mutant, was intensively studied. SS2-2 was generated by ethylmethane sulfonate (EMS) mutagenesis like other super-/hypernodulating mutants, nts382 and nts1116. To identify DNA variation at 67 SSR loci, the simple sequence repeat (SSR) polymorphisms were detected with 46 out of 67 primer pairs among the wild types. The only polymorphic SSR marker between SS2-2 and its wild-type ancestor was Satt294 on LG C1 instead of LG H where a super-/hyperndulating gene located. Sequencing data of amplicons using primers flanking the Satt294 for Sinpaldalkong 2 and SS2-2 indicated that the size variation was due to extra stretch of ATT repeat of the SSR motif in SS2-2, along with A→G transition. After SNPs were also surveyed between Sinpaldalkong 2 and SS2-2, only one SNP was detected in the exon region.