Quantitative Trait Loci Mapping Of Seed Traits Using Glycine Max×G. Soja Progeny

Wild soybean （Glycine soja） is an important genetic resource for cultivated soybean （Glycine max） improvement. Genetic study of important traits in the G.soja will provide a solid scientific basis for better understanding of the genetic mechanisms and practically using of those for the trait improvement. Three seed characters that distinguish cultivated with wild soybean are100-seed weight, protein content, and seed bloom. In the present research, we studied the genetic basis of those traits using the wild soybean accession ZYD2738that originated in China. The followings are the major results obtained from the research:1.Two genetic linkage maps were developed by using the F2populations of Jidou12×ZYD2738and Jidou9hao X ZYD2738which were derived from crossing of wild soybean ZYD2738with two cultivars Jidou12and Jidou9hao. The genome coverage ratio in the genetic linkage map reached69.2%. A total of121SSR makers were anchored with average distance of10.7cM in85individuals of Jidou12×ZYD2738population whereas143SSR makers were anchored with average distance of12.9cM in236individuals of Jidou9hao×ZYD2738population by the linkage map. A segregation distortion region on chromosome18was found in the map of Jidou9hao×ZYD2738, but the distortion loci had little effects on linkage map.2.The seed bloom locus （B1） was fine mapped, and the flanking makers were used to analysis the relationship between wild and cultivated germplasm. The results showed that the seed bloom may be controlled by one or two genes among six F2populations. By fine mapping in3072F3individuals, B1was further defined within43Kb region between Indel marker B1₁8and B1₉on chromosome13, containing5candidate genes which needed to be confirmed. A total of161G.max and100G.soja were compared to estimate the relationship between wild and cultivated soybean based on B1flanking markers. The results showed that the diversity of G.soja was higher than G.max. The diversity of accessions from geological distribution ranked as South region> North region> Huanghuai region but no obviously geographic distinction was found among the distribution of haplotype.3. The100-seed weight QTL qSWT₁3₁was fine mapped on chromosome13. F2:3and F2:4populations of Jidou12X ZYD2738and Jidou9hao X ZYD2738were used to map the QTL of100-seed weight in2environments （Shijiazhuang and Sanya）. Four QTL were mapped on chromosome5,7,10and13in Jidou12×ZYD2738population under Shijiazhuang environment, while2QTL were mapped on chromosome2and10in the same population under Sanya environment. In Jidou9hao×ZYD2738population, there were4QTL were mapped on chromosome9,13and14in Shijiazhuang, while2QTL were mapped on chromosome6and9in Sanya. The stable QTL qSWT₁3₁in2populations was fine mapped on chromosome13flanked by SSR marker Satt663and Sattl14that spans3.27Mb physical distance in advanced analysis using F6:7sub-population, then the region was reduced to1.49Mb based on association mapping using the data of17re-sequenced accessions.4. The F2:3progenies of Jidou12×ZYD2738and Jidou9hao×ZYD2738were used to discover the QTL for protein and oil content in Shijiazhuang environment. Six protein QTL and5oil QTL were identified in2populations. The qPRO₂0₁on chromosome20was a stable QTL under2populations. The allele from ZYD2738contributed2.18%more protein than that from Jidou12and1.29%more protein than that from Jidou9hao. In the population of Jidou9hao×ZYD2738, qPRO₂0₁showed epistatic role over the qPRO₁9_l on chromosome19. For maker assistant breeding, the protein content was40.43%in progenies selected by qPRO₂0₁compared to the41.15%in the progenies selected by both qPRO₁9₁and qPRO₂0₁.The QTL and germplasm lines with breeding value were detected and summarized in the present study. The results will be helpful to expand the genetic base in soybean improvement program by introducing favorite genes from Gsoja.