High-density Genetic Map Construction And Mapping Of The Homologous Transformation Sterility Gene In Wheat

HTS-1 was a novel pistillody mutant in wheat,unlike common wheat varieties,it exhibit that transforms all or parts of the stamen into pistils or pistil-like structures.Even sometimes 6 pistils or pistil-like structures along with 0 stamen in a floret can been observed.Thus,HTS-1 is highly valuable in the study of hybrid breeding and flower development in wheat.Previous studies have shown that pistillody in HTS-1 is controlled by main effect gene Pis1 and hts.The Pis1 gene had been mapping on chromosome 2D,but the hts gene has not been mapped and identified.To map and find the candidate gene of hts,we constructed a high-density linkage map base on the F₂population of 200 individuals derived from cross of HTS-1 with CM28TP by the next generation sequencing GBS.The main results are as follows:1.A total of 1,027 F₂ individuals were obtained after HTS-1 and CM28TP hybridization.In this population there are 739 normal phenotypes and 288 pistillody.This population fitted to Mendel's 3:1 genetic law by chi-square test,indicating that a recessive effect gene controls the pistillody trait in HTS-1?CM28TP plants.Then we selected 150 normal individuals and 50 pistillody individuals for a high-density linkage map construction.2.The map spans a total length of 2,779.12 cM,and the genetic distance of each chromosome ranging from 37.59 cM to 318.95 cM.The average distance is 1.04 cM.In addition,a high logarithm of the odds?LOD?score of 4.44 was detected on chromosome 4A,this showed that the hts gene located on the chromosome 4A in wheat.Using this map,the hts gene was mapped between GBS-SNP marker 4A₁09 and4A₁19.The genetic distance of those two markers was 1.66 cM and the physical distance was 5.2 Mb.Otherwise,the result of HTS-1 was hybridized with NT lines indicated that the F₁ generation of HTS-1?N4AT4B shown pseudodominance,this also suggested that hts gene located on the chromosome 4A.3.To find candidate genes,the location region of hts was enlarged to 7.2 Mb,which encompassed 752 protein-coding genes.After compared the 752 genes with the 206common DEGs between PS vs S and P vs S,a candidate gene Win 1?TaWin 1?was found.Real-time PCR analysis indicated that the TaWin1 gene has an unusually high expression level in the pistil and stamen differentiating stage of HTS-1,about 120 times higher than CM28TP.Further analysis indicated that the TaWin1 gene mainly expression in PS of HTS-1.Therefore,we speculate that TaWin 1 was the candidate gene of hts,and its overexpression may lead to transforms of stamens to pistil in wheat.This study laid a foundation for the study of the development of stamen and pistil and hybrids breeding in wheat.