QTL Mapping Of Vining Growth Habit And Plant Height In Soybean(Glycine Max)

Wild soybeans are valuable potential resources that can be used to provide elite alleles for soybean improvement and broaden soybean genetic basis,but the vining growth habit（VG）greatly limits their utilization in the breeding and improvement of cultivated soybeans.The divergence of vining growth among the offspring derived from different crosses indicating the complexity of the mechanisms regulating VG.A comprehensive understanding of the genetic mechanisms under VG will be helpful to the effective use of wild resources in soybean breeding and improvement.In this research,segregating populations were derived from crossing a cultivated soybean Zhonghuang39（ZH39）with two wild soybean ZYD2738 and ZYD3687,respectively.Bulk segregant analysis（BSA）and linkage mapping were performed to map VG and plant height（PH）related quantitative trait loci（QTL）.The main results are the followings:1.The F_2:3 lines were developed from a cross between ZH39 with ZYD2738.Illumina 200 K single nucleotide polymorphism（SNP）chip were implemented to bulked pools and their parents to identify SNPs associated with the major QTL related to VG.Eight genomic regions related with VG were detected on chromosomes 2,5,8,12,13,15,17 and 19.Three QTLs,qVG-2,qVG-17,qVG-19,were mapped on chromosomes 2,17 and 19 by using 60 SSR marker in these regions in F₂ populations.The QTLs identified in F₆ population using conventional mapping approach confirmed the efficiency of BSA in detection QTLs of VG.The major locus,qVG-19,identified in different populations explained more than 15%of the phenotypic variation.Two minor loci,qVG-2 and qVG-17,explained 6.79–10.11%and 2.77–6.69%of the phenotypic variation.2.The VG and PH of lines in F_6:7 population derived from a cross between ZH39 and ZYD2738were investigated in 2017 and 2018.Positive correlations were identified between of VG and PH.Three QTLs for PH,qPH-2,qPH-17 and qPH-19,were mapped on chromosomes 2,17 and 19.The qPH-17and qPH-19 were located in the same positions with qVG-17 and qVG-19,indicating possible pleiotropic effects on plant height and vining growth habit.3.Illumina 200 K SNP chip were implemented to bulked pools from a population of ZH39×ZYD3687.Six genomic regions were detected on chromosomes 4,6,7,12,13 and 19.Illumina 200 K SNP chip were used to genotyping 25 erect lines and 25 vining lines in RIL population of ZH39×ZYD3687.The qVG-19 was identified on chromosomes 19 and the positive allele in major locus qVG-19 inherited from wild soybean ZYD3687.These results revealed that QTL mapping efficiency by using individuals with of extreme phenotypes was higher than using DNA bulked pools.4.A pair of near isogenic lines（NIL）were generated from a cross between ZH39 and ZYD2738 by using marker-assisted selection.The genetic similarity of the NILs was 99.8%,with 91.2%polymorphic SNPs located within genomic region of qVG-19.NIL showed significantly grow habit difference under short-day,but similar performance under long-day condition,indicating that qVG-19 was affected by the length of photoperiod.5.Two Kompetitive allele-specific PCR（KASP）markers for qVG-19 were developed and validated,the accuracy of KASP assay is 99.0%,which substitute the SSR genotyping and accelerate fine mapping the major QTL of vining growth habit.