Plants photoreceptors perceive changes in light quality and intensity and thereby regulate plant vegetative growth and reproductive development. By screening a γ irradiation-induced mutant library of the soybean (Glycine max) cultivar “Dongsheng 7”, we identified Gmeny, a mutant with elongated nodes, yellowed leaves, decreased chlorophyll contents, altered photosynthetic performance, and early maturation. An analysis of bulked DNA and RNA data sampled from a population segregating for Gmeny, using the BVF-IGV pipeline established in our laboratory, identified a 10 bp deletion in the first exon of the candidate gene Glyma.02G304700. The causative mutation was verified by a variation analysis of over 500 genes in the candidate gene region and an association analysis, performed using two populations segregating for Gmeny. Glyma.02G304700 (GmHY2a) is a homolog of AtHY2a in Arabidopsis thaliana, which encodes a PΦB synthase involved in the biosynthesis of phytochrome. A transcriptome analysis of Gmeny using the Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed changes in multiple functional pathways, including photosynthesis, gibberellic acid (GA) signaling, and flowering time, which may explain the observed mutant phenotypes. Further studies on the function of GmHY2a and its homologs will help us to understand its profound regulatory effects on photosynthesis, photomorphogenesis, and flowering time.

In recent years, continuous cropping has become a major constraint on soybean production in China, and thus, researching methods to improve soybean yield under this cropping pattern has become a research hotspot. This study aimed to explore whether cultivar improvement and different fertilization regimes could enhance the nutrient uptake and resource utilization of continuously cropped soybean, thereby elevating its yield potential. A total of 11 soybean cultivars were subjected to different fertilization treatments, with the leaf area index (LAI), net photosynthetic rate (Pn), radiation use efficiency (RUE), dry matter accumulation, crop growth rate (CGR), nitrogen content (NC), grain yield, yield components, and harvest index (HI) analyzed. Compared with early cultivars, current cultivars increased LAI, Pn, CGR, RUE, NC, dry matter accumulation, grains per plant, 100-seed weight, HI, and grain yield by 26.22%, 10.07%, 34.13%, 22.65%, 20.43%, 29.44%, 30.09%, 9.80%, 13.69%, and 15.88%, respectively, while decreasing the nitrogen requirement per 100 g grain by 20.08%. Similarly, compared with unfertilized plants, fertilized plants increased these indices by 23.93%, 14.08%, 53.38%, 39.01%, 29.53%, 42.49%, 16.95%, 23.35%, 10.49%, and 26.50%, respectively, while decreasing the nitrogen requirement per 100 g grain by 14.40%, with the highest yield observed by the 2006-era cultivar (Dennison) fed compound fertilizer. In conclusion, cultivar improvement and fertilization can improve the yield potential of continuously cropped soybean by enhancing light energy and optimizing nitrogen accumulation and consumption, and future research should focus more on breeding to further tap the production potential of continuously cropped soybean.

Defective seed filling, which manifests as seed wrinkling, severely impairs the yield and commercial quality of soybean crops. Soybean varieties independently developed in Heilongjiang Province exhibit distinct phenotypic variations in seed wrinkling across diverse ecological planting regions, whereas the molecular and physiological mechanisms driving such differences remain largely uncharacterized. In this study, two soybean genotypes with divergent heat resistance, namely, the heat-sensitive cultivar HH43 and the heat-tolerant cultivar HN76, were planted in three distinct ecological sites for comparative analysis. Statistical results indicated that ecological conditions serve as the predominant factor regulating seed-wrinkling variation, with high temperatures occurring during the seed-filling stage identified as the key abiotic stress trigger. Excessively high ambient temperatures triggered abnormal sucrose accumulation in the pod husks of heat-vulnerable HH43, disrupting the coupling relationship between sucrose metabolism and energy supply and thereby restricting starch biosynthesis in developing seeds. Transcriptome profiling combined with weighted gene co-expression network analysis (WGCNA) further demonstrated that heat stress significantly suppressed the expression of energy transport-related genes and induced the dysregulated expression of starch synthesis-associated genes in susceptible soybean plants, and these transcriptional alterations were further verified via qRT-PCR assays. Collectively, short-term extreme high temperatures interrupt the carbon transport and allocation process from pod husks to seeds in heat-sensitive soybean cultivars. By contrast, heat-tolerant genotypes can sustain a stable physiological metabolism and molecular regulatory networks to effectively cope with high-temperature stress during the seed-filling period.

Continuous cropping obstacles severely restrict soybean production; nitrogen application can alleviate continuous cropping obstacles. However, it remains unclear how nitrogen metabolism and nodulation differ between soybean cultivars with contrasting continuous cropping tolerance under varied nitrogen levels. In this study, two soybean cultivars, Liaodou 14 (L14, continuous-cropping-tolerant) and Liaodou 10 (L10, continuous-cropping-sensitive), were cultivated in a sand culture system. Three nitrogen levels, low (LN), medium (MN), and high (HN), were set with three soybean soil extract treatments, namely continuous cropping (CC), continuous cropping + sodium orthovanadate (CS), and crop rotation (CR). Key nitrogen metabolic enzyme activities and gene expression in leaves and fine roots, nodule number, nitrogenase activity, and nitrogen content were systematically determined. The results show that the CC treatment significantly inhibited nitrogen metabolism enzyme activities, gene expression, and nitrogen accumulation, whereas the HN treatment partially alleviated the growth-related inhibitory effects induced by continuous cropping, although HN treatment did not fully restore symbiotic nitrogen fixation function. Under the CC treatment, L14 exhibited superior performance over L10 for most measured parameters, except for GDH activity and GmNADH-GOGAT expression. Specifically, the leaf NR activity of L14 was 8.51% and 8.47% higher than that of L10 at the R1 and R6 growth stages, respectively. The maximum nodule number was observed under the HN treatment, while the highest nitrogenase activity occurred under the LN treatment. Most indicators under the CS treatment showed intermediate values between the CC and CR treatments. Collectively, through optimized nitrogen management, continuous-cropping-tolerant cultivars maintain higher enzyme activities, stable gene expression and efficient nitrogen translocation and allocation, potentially alleviating continuous cropping obstacles and improving yield potential.