大豆GmSWEET39基因在高蛋白种质HPCD5中的定位、功能分析与育种应用OA

To explore the application value of the high-protein soybean new germplasm HPCD5 and its major quantitative trait locus(QTL)for seed protein content in variety breeding,this study performed linkage mapping using an F2 segregating population,combined with transcriptome and gene sequence analyses,to identify the major QTL controlling seed protein content.Furthermore,a recombinant inbred line(RIL)population was constructed,followed by phenotypic and genotypic characterization to clarify the breeding utilization efficiency of the major QTL.The results indicated that a QTL simultaneously regulating seed protein content,oil content,and 100-seed weight was detected in the interval of 2.4-5.7 Mb on soybean chromosome 15,which contains the gene GmSWEET39(GmSWEET10a,Glyma.15G049200)responsible for these three traits.Sequence and expression analyses revealed distinct variations in GmSWEET39 between HPCD5 and Nannong Caidou 5,and the expression level of this gene in the seeds of Nannong Caidou 5 at 30 days after flowering was significantly higher than that in HPCD5,demonstrating that GmSWEET39 is a key gene controlling seed protein content and other related traits in HPCD5.Using HPCD5 as the parent,hybrid combinations were developed with soybean varieties including Nannong 99-6,Wude,Xudou 14,and Zhonghuang 39,and an RIL population consisting of 334 families was established.Combined analysis of two-year phenotypic evaluation and genotypic detection of the RIL population identified multiple SNP markers associated with protein content,oil content,and 100-seed weight in the vicinity of GmSWEET39.Among these markers,the intragenic SNP marker TZX-94 explained 26.9%,29.9%,and 7.8%of the phenotypic variation for the three traits,respectively,confirming the stable selective effect of the GmSWEET39 haplotype from HPCD5 on soybean protein content,oil content,and 100-seed weight.Additionally,two InDel markers for GmSWEET39 were developed,enriching the molecular marker types of this gene.This study identified the major genetic locus derived from wild soybean in HPCD5 that controls seed protein content and other traits,expanded the allelic variation resources of GmSWEET39,verified its breeding application potential under multiple genetic backgrounds,and created several new high-protein soybean germplasms.These results provide important genetic resources and technical support for the molecular breeding of high-protein soybean varieties.