Search

Soybean (Glycine max [L.] Merr.) was domesticated from the wild annual progenitor Glycine soja (Sieb. & Zucc.) in the temperate zone of China. Through domestication and improvement, soybean agronomic traits and adaptability have been significantly altered. In this review, we discuss the ways in which genetic changes were selected in soybean to enable adaptation to diverse environmental conditions. Challenges and strategies are discussed for breeding new elite varieties from existing elite varieties. Finally, we propose a strategy to break the current genetic bottleneck in soybean breeding: de novo domestication, which utilizes the excellent genetic resources available in wild soybean and provides a feasible strategy for accelerating the soybean improvement process. Overall, this review serves as a guide to understand the genetic factors that have driven soybean domestication and improvement over thousands of years, promoting future generation of soybean cultivars that are optimized for high yield under stressful environmental conditions. [ABSTRACT FROM AUTHOR]

Soybean (Glycine max) is a typical short‐day plant, but has been widely cultivated in high‐latitude long‐day (LD) regions because of the development of early‐maturing genotypes which are photoperiod‐insensitive. However, some early‐maturing varieties exhibit significant responses to maturity under different daylengths but not for flowering, depicting an evident photoperiodic after‐effect, a poorly understood mechanism. In this study, we investigated the postflowering responses of 11 early‐maturing soybean varieties to various preflowering photoperiodic treatments. We confirmed that preflowering SD conditions greatly promoted maturity and other postflowering developmental stages. Soybean homologs of FLOWERING LOCUS T (FT), including GmFT2a, GmFT3a, GmFT3b and GmFT5a, were highly accumulated in leaves under preflowering SD treatment. More importantly, they maintained a high expression level after flowering even under LD conditions. E1 RNAi and GmFT2a overexpression lines showed extremely early maturity regardless of preflowering SD and LD treatments due to constitutively high levels of floral‐promoting GmFT homolog expression throughout their life cycle. Collectively, our data indicate that high and stable expression of floral‐promoting GmFT homologs play key roles in the maintenance of photoperiodic induction to promote postflowering reproductive development, which confers early‐maturing varieties with appropriate vegetative growth and shortened reproductive growth periods for adaptation to high latitudes. Summary statement: The photoperiodic after‐effect of early‐maturing soybean varieties is caused by the maintenance of high‐level expression of floral‐promoting GmFTs. This phenomenon indicates that maturity exhibits a stronger photoperiod sensitivity than flowering time, which ensures an appropriate vegetative growth and shortened reproductive growth of early‐maturing soybean varieties to adapt to high latitudes with significant changes in photoperiods from long day to short day in the growing season. [ABSTRACT FROM AUTHOR]

Seed size is a critical agronomic trait that influences the yield and appearance quality of soybeans, making it a primary breeding objective with significant economic value. While the molecular mechanisms that regulate soybean seed size remain largely unknown, several functional molecular targets have been applied in breeding to create larger grain size materials. In this study, we utilized the CRISPR/Cas9 system to induce the targeted mutagenesis of GmEOD1, which encodes the E3 ubiquitin ligase. The resulting homozygous soybean mutant of GmEOD1 exhibited larger seed size and 100-seed weight, with no significant change in the average seed weight per plant. The sum of crude protein and oil content increased significantly in mutants while fatty acid composition remained unchanged. We identified six haplotypes among 156 soybean cultivars, with Hap1 and Hap2 representing the majority of cultivars with relatively higher 100-seed weight, suggesting that sequence variations of GmEOD1 may correlate with seed weight. Transcriptomic analysis across five stages of seed development revealed that stages one–three mainly focused on cell cycle, growth, wall synthesis and modification, photosynthesis, and sugar metabolism; promoting cell growth, reproduction, and carbon accumulation; and providing key intermediates for substance synthesis. Stages four–five focused on polysaccharide catabolism, xylan metabolism, and nutrient pool activity, promoting the accumulation of dry matter, such as sugars, proteins, and lipids in seeds. Weighted gene co-expression network analysis (WGCNA) of modules related to seed size revealed 13 hub genes involved in seed development regulation. This study provides a valuable theoretical basis and excellent opportunities for genetic editing of germplasm cells with subsequent molecular soybean seed size breeding, facilitating easier seed selection to improve soybean quality. [ABSTRACT FROM AUTHOR]