Abstract:

Modern soybean cultivars typically display yellow to brown pods,while their wild ancestral specie,Glycine soja,possesses black pods.Pod color is an important domestication trait and phenotypic characteristic,which is strongly related to pod blasting habit and avoidance of predation.Two alleles were certified to control the pod color in soybean,among which the brown pod L2 gene has not been identified.In order to identify L2 gene on the soybean genome,and provide a theoretical basis for functional analysis and breeding application of brown pod related genes in soybean.The cultivated varieties Zhonglongyou 203(yellow pod)and wild varieties FF1235(black pod)were used as parents to generate an F₂ segregating population for genetic analysis in this study.The BSA-seq was performed using two gene pools which were constructed by brown pod and yellow pod individuals from the F₂ population,respectively.On this basis,recombinant exchange individuals were analysed.The results showed that brown pod was a quality trait controlled by a pair of alleles in soybean.The brown pod L2 gene was located in the 0—0.75 Mb region of Chromosome 3.By further use of 7 polymorphic InDel markers in fine mapping,the candidate interval was finally delimited between Indel-L2-3 and Indel-L2-6 with 344 kb physical distance.There were 32 candidate genes in the interval,among which Glyma.03G005700 gene was annotated as isopropylmalate polymerase.Glyma.03G005700 gene is highly homologous to the discovered black pod gene L1 (Glyma.19G120400),which may be responsible for converting 4-hydroxypyruvate into eucomic acid and piscidic acid,and may be a key gene in the regulating the formation of brown pod in soybean.

Key words: Soybean, Pod color, Mapping, BSA-seq