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As soybean plays an indispensable role in the supply of vegetable oil and protein, balancing the relationship between seed quality and yield traits according to human demand has become an important breeding goal for soybean improvement. Here, 256 intraspecific recombinant inbred lines (RILs), derived from a cross between Qi Huang No.34 (QH34) and Ji Dou No.17 (JD17), were used for quantitative trait loci (QTLs) mapping with remarkable four chemical and physical properties with a purpose for exploring the distribution of excellent alleles in germplasm resources in China. A total of 25 QTLs were detected, of which 10 QTLs inherited the alleles from the parent QH34. Pedigree research on favorable alleles on these QTLs showed the process of excellent alleles pyramided into QH34. Meta-analysis of the 25 QTLs by comparing with existed QTLs in previous study identified 17 novel QTLs. QTLs with pleiotropic effects have been detected. Furthermore, three representative elite recombinant inbred lines in different locations that have great potential in soybean breeding were selected, and finally, four seed weight-related candidate genes were identified. The discovery of these QTLs provides a new guidance for combining the diversity and rarity of germplasm resources, which can effectively increase population genetic diversity and broaden genetic basis of varieties. [ABSTRACT FROM AUTHOR]

Seed oil content is one of the most important quantitative traits in soybean (Glycine max) breeding. Here, we constructed a high-density single nucleotide polymorphism linkage map using two genetically similar parents, Heinong 84 and Kenfeng 17, that differ dramatically in their seed oil contents, and performed quantitative trait loci (QTL) mapping of seed oil content in a recombinant inbred line (RIL) population derived from their cross. We detected five QTL related to seed oil content distributed on five chromosomes. The QTL for seed oil content explained over 10% of the phenotypic variation over two years. This QTL was mapped to an interval containing 20 candidate genes, including a previously reported gene, soybean RING Finger 1a (RNF1a) encoding an E3 ubiquitin ligase. Notably, two short sequences were inserted in the GmRNF1a coding region of KF 17 compared to that of HN 84, resulting in a longer protein variant in KF 17. Our results thus provide information for uncovering the genetic mechanisms determining seed oil content in soybean, as well as identifying an additional QTL and highlighting GmRNF1a as candidate gene for modulating seed oil content in soybean. [ABSTRACT FROM AUTHOR]

Summary: Seed morphology and quality of cultivated soybean (Glycine max) have changed dramatically during domestication from their wild relatives, but their relationship to selection is poorly understood. Here, we describe a semi‐dominant locus, ST1 (Seed Thickness 1), affecting seed thickness and encoding a UDP‐D‐glucuronate 4‐epimerase, which catalyses UDP‐galacturonic acid production and promotes pectin biosynthesis. Interestingly, this morphological change concurrently boosted seed oil content, which, along with up‐regulation of glycolysis biosynthesis modulated by ST1, enabled soybean to become a staple oil crop. Strikingly, ST1 and an inversion controlling seed coat colour formed part of a single selective sweep. Structural variation analysis of the region surrounding ST1 shows that the critical mutation in ST1 existed in earlier wild relatives of soybean and the region containing ST1 subsequently underwent an inversion, which was followed by successive selection for both traits through hitchhiking during selection for seed coat colour. Together, these results provide direct evidence that simultaneously variation for seed morphology and quality occurred earlier than variation for seed coat colour during soybean domestication. The identification of ST1 thus sheds light on a crucial phase of human empirical selection in soybeans and provides evidence that our ancestors improved soybean based on taste. [ABSTRACT FROM AUTHOR]

Male‐sterile plants are used in hybrid breeding to improve yield in soybean (Glycine max (L.) Merr.). Developing the capability to alter fertility under different environmental conditions could broaden germplasm resources and simplify hybrid production. However, molecular mechanisms potentially underlying such a system in soybean were unclear. Here, using positional cloning, we identified a gene, MALE STERILITY 3 (MS3), which encodes a nuclear‐localized protein containing a plant homeodomain (PHD)‐finger domain. A spontaneous mutation in ms3 causing premature termination of MS3 translation and partial loss of the PHD‐finger. Transgenetic analysis indicated that MS3 knockout resulted in nonfunctional pollen and no self‐pollinated pods, and RNA‐seq analysis revealed that MS3 affects the expression of genes associated with carbohydrate metabolism. Strikingly, the fertility of mutant ms3 can restore under long‐d conditions. The mutant could thus be used to create a new, more stable photoperiod‐sensitive genic male sterility line for two‐line hybrid seed production, with significant impact on hybrid breeding and production. [ABSTRACT FROM AUTHOR]

Soybean mosaic virus (SMV) is the most prevalent viral pathogen in soybean. In China, the SMV strains SC and N are used simultaneously in SMV resistance assessments of soybean cultivars, but the pathogenic relationship between them is unclear. In this study, SMV strains N1 and N3 were found to be the most closely related to SC18. Moreover, N3 was found to be more virulent than N1. A global pathotype classification revealed the highest level of genetic diversity in China. The N3 type was the most frequent and widespread worldwide, implying that SMV possibly originated in China and spread across continents through the dissemination of infected soybean. It also suggests that the enhanced virulence of N3 facilitated its spread and adaptability in diverse geographical and ecological regions worldwide. Phylogenetic analysis revealed prominent geographical associations among SMV strains/isolates, and genomic nucleotide diversity analysis and neutrality tests demonstrated that the whole SMV genome is under negative selection, with the P1 gene being under the greatest selection pressure. The results of this study will facilitate the nationwide use of SMV-resistant soybean germplasm and could provide useful insights into the molecular variability, geographical distribution, phylogenetic relationships, and evolutionary history of SMV around the world. [ABSTRACT FROM AUTHOR]

Soybean seed appearance quality greatly affects the marketability. The objective of this study was to identify the quantitative trait loci (QTLs) that control the appearance quality of soybean seeds. A total of 256 recombinant inbred lines from Qi Huang No.34 × Ji Dou No.17 were utilized for QTL mapping. We innovatively applied a machine vision system to quantify the seed appearance of each line. As a result of QTL mapping, a total of 145 QTLs for the machine vision parameters were detected across three environments. We integrated QTLs mapped overlapped and obtained 16 QTL hotspots in total. Of these hotspots, hotspot-4–1 was suggested to be a major locus controlling seed size, and hotspot-15 was identified to affect the seed color and texture. The mapping for principal components of the seed appearance also supported it. This study comprehensively dug up the QTLs for seed appearance quality of soybean cultivars while providing an efficient method for phenotyping of seed appearance. These results would contribute to dissecting the genetic bases of seed appearance quality for the improvement of soybean. [ABSTRACT FROM AUTHOR]