Submitted to: Biennial Conference on Molecular and Cellular Biology of the Soybean
Publication Type: Abstract Only
Publication Acceptance Date: July 29, 1998
Publication Date: N/A
Technical Abstract: The four hypernodulating mutants derived from mutagenized Williams are genetically controlled by a single recessive gene (rj7). The objectives of the present study were to identify molecular markers associated with this mutant gene using PCR-based DNA polymorphism analysis, and to construct a genetic linkage map of the chromosomal region around the rj7 locus. Genomic DNA of two parents, Harosoy 63 and NOD1-3, and 122 F2 plants derived from this cross were isolated using the CTAB method. PCR amplifications of SSR, RAPD, and AFLP were performed. Initially, the two parents and two contrasting DNA pools were used for bulked segregant analysis to identify markers linked to this gene. Subsequently, segregation analysis was conducted in an F2 mapping population for the construction of a genetic linkage map. Map distances in cM were estimated using the MAPMAKER program. The results indicated that no SSR markers were found to be linked to the rj7 locus, while four RAPD and six AFLP markers were linked to this gene. Of the linked AFLP markers, the E3/M8-a and E5/M5-a were mapped closely to the rj7 locus at 2.3 and 7.4 cM, respectively. The remaining AFLPs and the RAPDs were relatively distal to the locus. Further examination to confirm the inheritance in F4 progenies isolated from F2 hypernodulating individuals and backcrosses (BC1 and BC2) indicated that these linked markers were heritable in descendants. In addition to the NOD1-3 mutant, three other NOD mutants and the En6500 mutant, which was isolated from the mutagenized Enrei cultivar, were also tested for the presence of these markers. The results were in agreement with the conclusions of our previous work on the involvement of an allelic gene in the NOD mutants and the En6500.