Qianli Dong

As a globally important leguminous crop, soybean (Glycine max L.) serves as a vital source of edible oils and proteins for humans and livestock. Oils in leaves can help crops combat fungal infections, adapt to temperature changes via fatty acid modulation, and support resource recycling during leaf senescence. However, accumulating oils in leaves is a fundamental challenge due to the need to balance the inherently competing photosynthesis and fatty acid biosynthesis processes within chloroplasts. RETICULATA-RELATED (RER), known to regulate chloroplast function and plastid metabolism in Arabidopsis, plays an essential role in leaf development. Here, 14 non-redundant GmRER genes were identified in soybean and phylogenetically classified into four subclades. Most Arabidopsis RER genes were evolutionarily preserved as gene duplicates in soybean, except for GmRER5 and GmRER6. RNA secondary structures spanning the coding sequences (CDSs), the 5′- and 3′- untranslated regions (UTRs) of GmRERs, displayed exceptional structural plasticity in CDSs, while exhibiting limited conservation in UTRs. In contrast, protein structures retained conserved folds, underscoring evolutionary constraints on functional domains despite transcriptional plasticity. Notably, GmRER4a and GmRER4b represented an exceptional case of high similarity in both protein and RNA structures. Expression profiling across fourteen tissues and three abiotic stress conditions revealed a dynamic shift in expression levels between leaf-predominant and root-enriched GmRER paralogs after stress treatments. A comparative transcriptome analysis of six soybean landraces further revealed transcriptional polymorphism in the GmRER family, which was associated with the expression patterns of lipid biosynthesis regulators. Our comprehensive characterization of GmRERs may offer potential targets for soybean breeding optimization in overall plant oil production.

Soybean, a globally important crop, is a typical short-day and thermophilic plant. Continuous efforts are necessary to elucidate the genetic basis of its essential traits. In this study, we assembled a collection of 203 soybean varieties, all of which are well suited for cultivation in the northeastern region of China. We assessed 15 agronomic traits under three distinct environments, noting substantial phenotypic variations in the panel and stable correlations among traits. The population structure analysis, based on genotyping-by-sequencing (GBS) data, revealed seven subpopulations within the panel and significant gene flows among these subpopulations. Through genome-wide association studies (GWASs), we identified 64 significantly associated loci (SALs) for 15 traits and unveiled the genetic interconnections between yield and related traits. Additionally, we highlighted a few candidate genes within SALs for yield and related traits. Finally, we evaluated the genomic prediction performances of four distinct methods across the three environments, revealing the significant influence of environmental factors on predictive accuracies. We found that rrBLUP is suitable for most traits, though specific traits may benefit from more complex machine learning models. Our findings establish a foundation for the future research of genetic mechanisms of soybean agronomic traits and the application of genomic selection in soybean breeding.

Soybean is a primary source of plant-based oil and protein for human diets. Seed size and weight are important agronomic traits that significantly influence soybean yield. Despite their importance, the genetic mechanisms underlying soybean seed size and weight remain to be fully elucidated. In order to identify additional, major quantitative trait loci (QTL) associated with seed size and weight, we developed segregating populations by crossing a large-seeded soybean variety “Kebaliang” with a small-seeded soybean variety “SUZUMARU”. We evaluated seed length, width, thickness, and hundred-seed weight across two generations, F₄ and F₅, in 2022 and 2023. Employing bulked segregate analysis with whole-genome resequencing (BSA-seq), we detected 18 QTLs in the F₄ population and 12 QTLs in the F₅ population. Notably, six QTLs showed high stability between the two generations, with five derived from two pleiotropic loci (qSS4-1 and qSS20-1) and one specific to seed width (qSW14-1). Further validation and refinement of these loci were carried out through linkage mapping using molecular markers in the F₅ population. Additionally, we identified 18 candidate genes within these stable loci and analyzed their sequence variations and expression profiles. Together, our findings offered a foundational reference for further soybean seed size research and unveiled novel genetic loci and candidate genes that could be harnessed for the genetic enhancement of soybean production.

Plants, as sessile organisms, deploy transcriptional dynamics for adapting to extreme growth conditions such as cold stress. Emerging evidence suggests that chromatin architecture contributes to transcriptional regulation. However, the relationship between chromatin architectural dynamics and transcriptional reprogramming in response to cold stress remains unclear. Here, we apply a chemical-crosslinking assisted proximity capture (CAP-C) method to elucidate the fine-scale chromatin landscape, revealing chromatin interactions within gene bodies closely associated with RNA polymerase II (Pol II) densities across initiation, pausing, and termination sites. We observe dynamic changes in chromatin interactions alongside Pol II activity alterations during cold stress, suggesting local chromatin dynamics may regulate Pol II activity. Notably, cold stress does not affect large-scale chromatin conformations. We further identify a comprehensive promoter-promoter interaction (PPI) network across the genome, potentially facilitating co-regulation of gene expression in response to cold stress. Our study deepens the understanding of chromatin conformation-associated gene regulation in plant response to cold.

Associations between 3D chromatin architectures and epigenetic modifications have been characterized in animals. However, any impact of DNA methylation on chromatin architecture in plants is understudied, which is confined to Arabidopsis thaliana. Because plant species differ in genome size, composition, and overall chromatin packing, it is unclear to what extent findings from A. thaliana hold in other species. Moreover, the incomplete chromatin architectural profiles and the low‐resolution high‐throughput chromosome conformation capture (Hi‐C) data from A. thaliana have hampered characterizing its subtle chromatin structures and their associations with DNA methylation. We constructed a high‐resolution Hi‐C interaction map for the null OsMET1‐2 (the major CG methyltransferase in rice) mutant (osmet1‐2) and isogenic wild‐type rice (WT). Chromatin structural changes occurred in osmet1‐2, including intra‐/inter‐chromosomal interactions, compartment transition, and topologically associated domains (TAD) variations. Our findings provide novel insights into the potential function of DNA methylation in TAD formation in rice and confirmed DNA methylation plays similar essential roles in chromatin packing in A. thaliana and rice.

Polyploidization has played a prominent role in the evolutionary history of plants. Two recent and sequential allopolyploidization events have resulted in the formation of wheat species with different ploidies, and which provide a model to study the effects of polyploidization on the evolution of gene expression. In this study, we identified differentially expressed genes (DEGs) between four BBAA tetraploid wheats of three different ploidy backgrounds. DEGs were found to be unevenly distributed among functional categories and duplication modes. We observed more DEGs in the extracted tetraploid wheat (ETW) than in natural tetraploid wheats (TD and TTR13) as compared to a synthetic tetraploid (AT2). Furthermore, DEGs showed higher Ka/Ks ratios than those that did not show expression changes (non-DEGs) between genotypes, indicating DEGs and non-DEGs experienced different selection pressures. For A-B homeolog pairs with DEGs, most of them had only one differentially expressed copy, however, when both copies of a homeolog pair were DEGs, the A and B copies were more likely to be regulated to the same direction. Our results suggest that both cis- and inter-subgenome trans-regulatory changes are important drivers in the evolution of homeologous gene expression in polyploid wheat, with ploidy playing a significant role in the process.