Inheritance and mapping of drought tolerance in soybean at seedling stage using bulked segregant analysis

Occurrence of drought under rainfed conditions is the foremost factor responsible for yield reduction in soybean. Developing soybean cultivars with an inherent ability to withstand drought would immensely benefit the soybean production in rainfed areas. In the present study, F2 derived mapping populations were developed by crossing drought tolerant (PK 1180, SL 46) and susceptible (UPSL 298, PK 1169) genotypes to investigate the inheritance of seedling survival drought mechanisms and to identify simple-sequence repeat (SSR) markers associated with them, using bulked segregant analysis. Parents as well as a F2 derived mapping population were screened for drought tolerance based on seedling survivability under controlled conditions. Segregation analysis of F2 population derived from a cross between PK 1180 × UPSL 298 was previously shown to have a 3:1 tolerant to susceptible ratio and a probability of 0.61 at a χ2 (3:1) value of 0.258. This was confirmed in another F2 population derived from a cross between PK 1169 × SL 46 with a χ2 (3:1) value of 0.145 obtained at a probability of 0.70. One SSR marker Satt277 showed polymorphism between contracting bulks (tolerant and susceptible) out of 50 polymorphic markers identified during parental polymorphism. Single marker analysis suggested that the marker, Satt277 is linked to seedling survival drought tolerance and is located on chromosome linkage group C2 (chr 6) with a map distance of 3.40 cM. The tolerant genotypes identified could be used as a donor in soybean improvement programs. The marker identified can be used in marker-assisted selection while screening large collection of germplasm.