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.

中文翻译：

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大豆苗期耐旱性的遗传和定位分析

在雨养条件下发生干旱是导致大豆减产的首要因素。开发具有内在抗旱能力的大豆品种将极大地有利于雨养地区的大豆生产。在目前的研究中，F2通过杂交耐旱（PK 1180、SL 46）和易感（UPSL 298、PK 1169）基因型开发衍生的作图种群，以研究幼苗存活干旱机制的遗传并鉴定与其相关的简单序列重复（SSR）标记，使用批量分离分析。父母以及一个F2基于受控条件下的幼苗生存能力，对衍生的绘图种群进行耐旱性筛选。偏析分析F2来自 PK 1180 × UPSL 298 杂交的种群先前显示具有 3:1 的耐受易感比和 0.61 的概率χ2(3:1)值为 0.258。这在另一个F2种群来源于 PK 1169 × SL 46 与χ2(3:1)以 0.70 的概率获得 0.145 的值。在亲本多态性期间鉴定的 50 个多态性标记中，一个 SSR 标记 Satt277 显示出收缩体（耐受和易感）之间的多态性。单标记分析表明，标记Satt277与幼苗存活耐旱性连锁，位于染色体连锁群C2（chr 6）上，图谱距离为3.40 cM。鉴定出的耐受基因型可用作大豆改良计划的供体。鉴定的标记可用于标记辅助选择，同时筛选大量种质。