Recently, Professor Wang Zhenyu's team from the South China Academy of Sciences Southern Crop Germplasm Research Institute, in collaboration with Professor Zhao Tuanjie's team from the National Center for Soybean Improvement at Nanjing Agricultural University, conducted research to decipher the genetic loci and domestication genes regulating soybean grain weight. The related findings were published in "Theoretical and Applied Genetics".
As the saying goes, "Better to eat without meat than to be without beans." Soybeans are a valuable source of plant protein and a healthy edible plant oil. China, the birthplace of soybeans, has a long history of cultivation and consumption. However, China's soybean demand has long relied on imports to meet its needs. From 2020 to 2023, China's average annual soybean imports exceeded 90 million tons, with an external dependency rate of over 80%, highlighting a significant dependency issue.
Dr. Li Yang, the first author of the paper and a doctoral student at the Southern Crop Germplasm Research Institute of the South China Academy of Sciences, stated that soybean hundred-seed weight is an important agronomic trait affecting soybean yield. While wild soybeans have a hundred-seed weight of only about 5 grams, cultivated soybeans selected by humans can reach 20 grams. Deciphering the molecular genetic basis of soybean hundred-seed weight, identifying major effect genetic loci, and key candidate genes are of great significance for soybean high-yield and quality breeding and improvement.
This study conducted hundred-seed weight trait surveys on two soybean populations, combined with SNP data obtained from population sequencing, and utilized methods such as genome-wide association analysis (GWAS) to identify genetic loci (QTLs) and target genes regulating soybean hundred-seed weight. In the first population, a total of six QTLs significantly associated with soybean hundred-seed weight were identified. Among them, a major effect QTL for soybean hundred-seed weight on chromosome 4 was consistently localized in both populations, indicating its stability and reliability.
To further explore the target candidate genes within this QTL, combined with linkage disequilibrium analysis of the candidate region, gene functional analysis, and expression pattern analysis, Cytochrome P450 gene GmCYP82C4 was selected as the final candidate gene, and sequence variations in its promoter were significantly associated with soybean hundred-seed weight.
Thus, based on the sequence variations within GmCYP82C4, haplotype analysis was conducted in the second population, which included wild soybeans, local varieties, and breeding varieties (a total of 345 materials). The study revealed eight GmCYP82C4 haplotypes (Hap1-8), among which the excellent haplotype Hap2 (average hundred-seed weight 18.27) was found to be much more prevalent in local varieties (92.4%) and cultivated varieties (74.1%) compared to its prevalence in wild soybeans (33.3%), indicating that the GmCYP82C4 gene may have been selected during the domestication and improvement of soybeans. Further genetic diversity and molecular evolution analysis of GmCYP82C4 and its upstream and downstream intervals based on genomic data provided additional evidence of strong selection during the domestication and improvement of soybeans.
The discovery of QTLs regulating soybean hundred-seed weight and the domestication gene GmCYP82C4 in this study provides genetic and gene resources for high-yield soybean breeding.
Related Paper Information: https://doi.org/10.1007/s00122-024-04571-7
