Genetic Mapping And Candidate Genes Analysis Of Regulatory Loci Of Soybean Flower Color

Flower color is one of the most basic and important biological traits of plants,it is also one of the phenotypic traits with the highest usage in agricultural production.Flower color has important biological significance in maintaining plant genetic diversity and increasing yield.At present,multiple gene loci regulating flower color such as W₁,W₂,W₃,W₄,W_m and W_p,all have been found in soybean,gene cloning and functional identification have been completed and the relevant molecular regulatory mechanism has been preliminarily resolved.In the research,the wild soybean purple-throated flower color material JLB1 was used as the female parent and the cultivated soybean variety JIYU 47 was crossed to obtain a derived F₂ generation isolation population,mixed pools of three typical traits of white flower,purple flower and purple throat were constructed.Finally,the mutation site was analyzed by bulked sergeant analysis（BSA）to preliminarily locate the gene loci related to soybean flower color control.Based on variant site analysis,insertion-deletion（In Del）is developed to analyze the single-plant polymorphism and genetic mapping of the F₂ generation population.Then we predict the candidate gene for purple throat trait through gene function annotation and transcriptional regulation differential expression analysis in the localization interval.The main findings are as follows:（1）The flower colors of 208 plants are counted and recorded during the peak flowering period of the F₂ generation isolated population,including 104 purple-throated plants in purple flowers,8 plants without purple throat in purple flowers,66 plants with purple throat in white flowers and 60 plants without purple throat in white flowers.By observing the flower color separation ratio of a single plant in the F₁ and F₂ generation populations,it is found that the ratio of purple-throated material to non-purple-throated materials are about 3:1（chi-square test:P=0.001,χ²=17065.8）,which conform to Mendel’s law of inheritance,indicating that a dominant gene regulate purple throat and controlled by a single gene.（2）F₂ generation single-plant genomic DNA was extracted to construct three typical mixing pools of purple flower,white flower and purple throat.The gene regulating purple throat is mapped between 37 285 034 bp～41 740 288 bp on chromosome 17 by BSA sequencing analysis.（3）9 pairs of In Del molecular markers are developed to locate candidate sites in a single strain of F₂ generation isolated population and genetic mapping is performed through Join Map 4.0 software,finally the candidate genes are mapped between the molecular markers In Del-7 and In Del-8,with a genetic distance of0.28 c M and 0.32 c M and a physical distance about 609.46 Kb.（4）Functional annotation and sequence alignment analysis of all genes in the candidate genes interval,combined with the differential expression of genes in the interval in the transcriptome sequencing data,the candidate genes related to flower color are screened.It is speculated that Glyma.17G230000 and Glyma.17G231900are candidates for regulating purple throat trait.