Genetic transformation is an essential tool for functional genomics and genetic improvement in soybean (Glycine max L.). However, its application remains limited by strong genotype dependence, low transformation efficiency, and poor regeneration. Progress has recently been made to optimize Agrobacterium-mediated systems, physical DNA delivery methods, and tissue culture–free transformation systems. The introduction of developmental regulators, including WUSCHEL (WUS), BABY BOOM (BBM), WUSCHEL-related homeobox (WOX), and GROWTH-REGULATING FACTOR (GRF)–GRF-Interacting Factor (GIF) complexes, has improved the transformation efficiency and expanded the range of amenable soybean genotypes. This review summarizes the recent advances in soybean transformation technologies and regeneration-promoting factors, analyzes the major factors influencing transformation efficiency, and discusses future prospects for high-efficiency, genotype-flexible, and exogenous DNA-free gene- editing and breeding in soybean.

The content and composition of fatty acids are crucial determinants of soybean nutritional quality. In this study, we conducted an expression genome-wide association analysis (eGWAS) using 298 soybean germplasm accessions. We identified 904,984 high-quality SNP markers (MAF > 0.02, missing data ≤ 10

Phosphofructokinase (PFK), a core metabolic enzyme conserved across all organisms, plays a pivotal role in plant growth and development as well as in the regulation of responses to abiotic stresses. While the PFK gene family has been characterized in a variety of plant species and a partial identification in soybean has been reported recently, the complete repertoire and the functional roles of this gene family in soybean remain to be fully elucidated, with inconsistencies in gene number observed across different studies. In this study, we further performed a systematic genome-wide screening of soybean and identified a total of 27 GmPFK family members. Phylogenetic tree analysis further classified these members into three distinct subfamilies. Conserved structure analysis revealed that all GmPFKs contain the PFK domain (PF00365). Real-time quantitative PCR (qRT-PCR) analysis demonstrated that the GmPFK6 gene exhibited a significant upregulation of expression under salt stress. Furthermore, the GmPFK6 gene was cloned and introduced into soybean hairy roots. The results demonstrated that under salt stress, the root length and fresh weight of hairy roots from the control lines were significantly greater than those from the transgenic lines. In addition, under salt stress, the superoxide dismutase (SOD) activity in the control lines was significantly higher than that in the transgenic lines, while the malondialdehyde (MDA) content in the transgenic lines was significantly lower than that in the control lines.

Isopentenyltransferase (IPT) is the rate-limiting enzyme in cytokinin biosynthesis and plays a critical role in plant acclimation to abiotic stress. To explore soybean IPT genes, we performed genome-wide identification, bioinformatics analysis, and molecular experimental validation to systematically characterize the features and functions of the soybean IPT (GmIPT) gene family. We identified 15 GmIPT genes in the soybean genome, which are unevenly distributed across 12 chromosomes; their evolutionary expansion is primarily driven by whole-genome duplication events. Phylogenetic analysis of soybean IPT proteins with those from Arabidopsis, rice and maize clustered them into four groups, exhibiting lineage-specific functional specialization. GmIPT genes exhibit significant variations in conserved motifs, gene structure, and cis-acting elements; their promoter regions are enriched in light-responsive, abiotic stress-responsive, and hormone-responsive elements, indicating their involvement in complex transcriptional regulatory networks. Tissue expression profiling revealed that GmIPT7 and GmIPT10 are highly expressed in various tissues, whereas GmIPT14 shows specific expression in flowers and the shoot apical meristem. Transcriptomic analysis and qRT-PCR validation demonstrated that GmIPT7, GmIPT10 and GmIPT15 respond differentially to drought, salt and low-temperature stress, with GmIPT15 exhibiting a transient upregulation at 3 h (p < 0.01) followed by a gradual decline to levels close to the pre-treatment control at 6-12 h under low-temperature stress. We further performed haplotype analysis of GmIPT15 and identified a putative elite haplotype (hap1) associated with cold tolerance based on low-temperature germination index assessment. This study provides useful insights for the future functional characterization of plant IPT genes and offers potential genetic resources and molecular markers that may support molecular-assisted breeding for soybean abiotic stress tolerance.

Fructose-1,6-bisphosphate aldolase (FBA), as a key enzyme in energy metabolism, is widely present in organisms. Although FBA genes have been characterized in numerous plant species, their functional roles in soybean remain poorly understood. In this study, a total of 14 GmFBA genes were identified at the genome-wide level. Additionally, phylogenetic analysis divided all GmFBA family members into two divergent subclades. qRT-PCR analysis revealed that most GmFBA genes were markedly responsive to PEG6000 and salt stresses, among which GmFBA5 exhibited the strongest induction under salinity treatment. The heterologous expression of GmFBA5 in yeast was performed. The results showed that GmFBA5 markedly enhanced salt tolerance of yeast cells. Association analysis identified two distinct haplotypes of GmFBA5, and Haplotype 2 significantly enhances salt tolerance in soybean. These findings provide new insights into the potential role of GmFBA5 in soybean salt stress responses and provide candidate genetic resources for salt tolerance improvement.

Fusarium root rot, primarily caused by Fusarium solani, is a damaging soil-borne disease that restricts soybean growth and reduces yield. In the present study, a panel of 330 soybean germplasm accessions was inoculated with F. solani. Disease responses were evaluated using the disease severity index (DSI). The soybean accessions displayed substantial variation in their susceptibility to F. solani. Based on DSI, 39 accessions were classified as highly resistant, 94 as resistant, 125 as susceptible, and 72 as highly susceptible, accounting for 11.82%, 28.48%, 37.88%, and 21.82% of the panel, respectively. The genome-wide association study (GWAS) was performed using a genotyping dataset of 627,436 high-quality single nucleotide polymorphisms (SNPs) and two models, Fixed and random model Circulating Probability Unification (FarmCPU) and mixed linear model (MLM). Both GWAS models detected putative SNP associations across seven chromosomes. Based on SNP allelic-effect analysis and gene function annotation, eight genes were prioritized and subsequently evaluated by quantitative reverse transcription PCR (qRT-PCR) for their responses to F. solani infection. Two Kompetitive allele-specific PCR (KASP) markers, KASP-S13_37431242 and KASP-S13_37529208, were developed from resistance-associated SNPs on chromosome 13 and evaluated across the diverse soybean association panel used in this study. Accessions carrying the favorable genotypes of these markers were enriched for resistant germplasm, with positive predictive values of 65.52% and 66.67%, respectively, indicating their potential value for preliminary favorable-allele tracking and germplasm prioritization. Collectively, these results improve our understanding of the genomic components underlying soybean responses to F. solani. The identified loci, candidate genes, and KASP assays provide a basis for further functional validation and the development of multi-locus strategies for improving soybean resistance to Fusarium root rot.

Soybean root rot caused by Fusarium graminearum is an important soil-borne disease. It hinders seedling establishment and ultimately reduces soybean yield. Resistant germplasm and reliable molecular markers are therefore needed for resistance breeding. In this study, 336 soybean accessions were evaluated for resistance to F. graminearum root rot using the disease severity index (DSI), which ranged from 5.71 to 100.00 across the association panel. Genome-wide association analysis was performed using resequencing-based single nucleotide polymorphism (SNP) data with mixed linear model (MLM) and Fixed and random model Circulating Probability Unification (FarmCPU) models, which detected 117 and 113 candidate resistance-associated SNPs, respectively. Among these, 105 shared SNPs were used to define candidate genomic intervals containing 247 annotated genes. Based on Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment, functional annotation, and allelic-effect analysis, six candidate genes and their associated exonic SNPs were prioritized. Quantitative reverse transcription polymerase chain reaction (qRT-PCR) analysis showed infection-responsive expression patterns for all six candidate genes, with Glyma.17g202500 and Glyma.18g266700 showing stronger induction in the resistant accession. Two SNPs in these genes were converted into Kompetitive allele-specific PCR (KASP) assays. KASP-S17_32244510 and KASP-S18_55105706 were successfully developed for genotype screening, with screening efficiencies of 73.08% and 74.29%, respectively. These findings identify useful genetic targets and molecular markers for improving soybean resistance to root rot caused by F. graminearum.

Soybean is crucial to food processing and agricultural output. However, pests and diseases can easily impact soybeans, reducing their production. Soybean cyst nematode (SCN) is a soilborne pathogen that has a large geographic range, a long lifespan, and the potential to inflict substantial harm to the soybean industry. Persistent use of major resistance genes leads to a progressive loss of resistance; therefore, continuous identification of new soybean strains and genes is essential for continued sustainable soybean production. In this research, the SCN-resistant and SCN-sensitive germplasm DN-L10 and Heinong 37 were inoculated with SCN 3. After stress treatment, the stressed roots were collected for RNA-Seq analysis. The sequencing results screened out the differentially expressed gene GmbHLH18. The GmbHLH18 gene was cloned, and the overexpression vector pCAMBIA3300-GmbHLH18 was constructed. Agrobacterium infected soybean hairy roots and genetically modified the roots of DN50 soybeans, and transgenic root seedlings were obtained. The transgenically identified root seedlings were transplanted in soil infested with SCN 3, and resistance to root nematodes was determined by magenta staining. The secondary and tertiary structures of the protein, phosphorylation sites, as well as the hydrophilicity related to the GmbHLH18 gene were analyzed. Subsequently, the recombinant subcellular localization vector pCAMBIA1302-GmbHLH18 was employed. Agrobacterium was injected into tobacco leaves, and organelle-specific expression was observed. Finally, stress resistance-related indexes of the roots of overexpressing plants and WT plants under SCN 3 stress were measured. The results showed that overexpression and subcellular localization vectors were successfully constructed and transformed into Agrobacterium K599 and GV3101, respectively. The encoded protein had 1149 amino acids, a molecular weight of 95.76 kDa, an isoelectric point of 5.04, 60 phosphorylation sites, a tertiary structure of a-helix (36.39%), random coil (53.40%), extended chain (8.64%), and corner (1.57%), and was hydrophilic. The protein that the gene encoded was a nuclear-localized protein, according to the results of subcellular localization analysis. Moreover, the Agrobacterium-induced hairy root test revealed that the number of overexpressed pCAMBIA3300-GmbHLH18 transgenic roots in the unit area of DN50 was substantially lower than in the control group, which at first suggested that the gene had partial resistance to SCN 3. Stress resistance-related indexes suggest that the contents of POD, SOD, and proline in the overexpressing root significantly increase after SCN 3 stress, demonstrating that this gene can enhance the plant’s resistance to the SCN 3 pathogen. Future research could focus on further elucidating the molecular mechanism underlying the gene’s resistance to SCN 3 and exploring its potential application in breeding soybean varieties with enhanced resistance.

Fatty acid transporters (FAXs) play an important role in fatty acid synthesis by facilitating transport fatty acids from the plastid to the endoplasmic reticulum. This process is essential for providing precursor substances necessary for triglycerides (TAGs). Although FAX genes have been identified in variety of plant species, the identification and molecular functions of the GmFAX gene members in soybean are still unclear. In this study, soybean FAX genes were identified through the utilization of the Phytozome (v13) and NCBI online websites. Subsequently, phylogenetic trees, expression patterns, gene structures, and qRT-PCR were analyzed. A total of eight GmFAX members were identified at the whole genome level, and further phylogenetic analysis revealed that these members can be categorized into four subfamilies. In addition, all members of GmFAX contain a highly conserved domain Tmemb_14. Through qRT-PCR analysis, it was found that the expression level of the GmFAX8 gene is relatively high in leaves and stems. Further investigation revealed that the total fatty acid content in hairy roots overexpressing the GmFAX8 gene was significantly greater than that observed in the control strain. The results presented above suggest that the GmFAX8 gene may play an important role in the accumulation of oil within soybeans.

Soybean (Glycine max) is a major crop for grain and oil production worldwide. However, soybean cyst nematode (SCN) disease is a serious threat to soybean cultivation, causing major challenges for agriculture in China and globally. In this study, 306 soybean germplasms were evaluated for resistance to SCN HG type 0 using the female index (FI), a metric quantifying nematode reproduction on soybean roots. Furthermore, we performed a genome-wide association analysis study using 1,332,548 high-density single nucleotide polymorphism (SNP) markers. Through this analysis, the study identified quantitative trait nucleotides (QTN) and pinpointed candidate genes that are linked to resistance against SCN HG type 0. A total of 77 SNPs and 117 candidate genes associated with soybean resistance to SCN HG type 0 were identified. Subsequently, two kompetitive allele-specific PCR (KASP) markers, S19_rs8522772 and S19_rs8384176, along with four cleaved amplified polymorphic sequence (CAPS) markers (S19_rs838271, S19_rs8522589, S19_rs8466511 and S19_rs8481473) were developed. These markers were found to be closely linked to soybean resistance to SCN based on the results of beneficial allele analysis of candidate genes. These markers not only expanded the soybean germplasm resource, but also provided a solid foundation for molecular breeding of soybean varieties resistant to SCN.

The plant stress response mechanism is activated by biotic and abiotic stresses, but its continuous activation typically affects growth. The role of ferritin in regulating biomass accumulation has been extensively characterized in diverse plant species; however, the underlying mechanisms through which it contributes to salt stress tolerance and Fusarium resistance remain poorly understood. Here, we confirm that overexpression of ferritin leads to iron accumulation and Fe3+ sequestration in both aboveground and roots, activating the iron uptake and transport system. More importantly, GmFER1 enhances salt stress tolerance and Fusarium resistance. First, GmFER1 is localized in chloroplasts and significantly induced by salt stress and Fusarium infection. Overexpression of GmFER1 increases soybean yield per plant by enhancing net photosynthetic rate and Rubisco enzyme activity, without activating the reactive oxygen scavenging mechanism. Under salt stress, GmFER1 enhances resistance by improving the activities of SOD and CAT enzymes, as well as Na+ efflux capacity. Under Fusarium infection, GmFER1 enhances resistance to the pathogen by boosting antioxidant capacity. Moreover, iron-deficiency tests revealed that increased CAT and SOD activities under salt stress are linked to iron ions accumulation. Lastly, we analysed the effects of GmFER1 gene variation on salt tolerance, disease resistance and 23 agronomic traits related to yield and quality. Further analysis of GmFER1 gene variation revealed that the Hap2 haplotypes could potentially enhance salt resistance, disease resistance, pod number and oil content in soybean. Our research offers a new way to reduce growth penalties while boosting plant resistance to salt stress and Fusarium infection.

Using the cotyledonary node method, four traits related to callus induction rate were identified in 185 soybean germplasm resources. Cultivation of callus tissue is crucial for soybean (Glycine max (L.) Merr.) genetic transformation and functional genomics studies. Identifying genes associated with the induction rate of soybean callus tissue is therefore essential for biotechnological breeding and for understanding the molecular genetic mechanisms of soybean regeneration. The efficiency of genetic transformation impacts the breeding rate of soybeans, with its success rate dependent on the soybean regeneration system. Subsequently, whole genome association analysis (GWAS) and multidimensional functional validation were conducted. GWAS identified 66 significantly associated SNP loci corresponding to the four traits. Expression analysis in extreme phenotypes highlighted four candidate genes: Glyma.12G164100 (GmARF1), Glyma.12G164700 (GmPPR), Glyma.02G006200 (GmERF1), and Glyma.19G128800 (GmAECC1), which positively regulate callus formation. Overexpression and gene-editing assays in hairy roots confirmed that these genes significantly enhanced callus formation rate and density, with GmARF1 exerting the most prominent effect. Hormone profiling revealed elevated levels of gibberellin (GA), auxin (IAA), cytokinin (CTK), and other phytohormones in transgenic lines, consistent with enhanced responsiveness to exogenous GA. Overall, the results suggest that these four candidate genes may promote soybean regeneration, with GmARF1 showing the most pronounced effect. These results provide valuable genetic resources for improving soybean regeneration efficiency and accelerating genetic transformation-based breeding.

The bile acid: sodium symporter (BASS) plays a pivotal role in plant growth, development, and response to abiotic stress. In this study, eight members of the BASSs group were identified through genome-wide screening. Additionally, employing phylogenetic analysis allowed for the categorization of the BASS gene family into five distinct subfamilies. The localization of GmBASSs in young tobacco leaves was primarily observed within chloroplasts using confocal microscopy. The qRT-PCR analysis revealed that a significant response was observed in the majority of GmBASSs genes toward abiotic stress, such as NaCl, NaHCO3, and 20% PEG6000. The GmBASSs gene was also observed to display distinct expression patterns across various tissue. It is noteworthy that the GmBASS2-2 gene exhibits a remarkably high level of upregulation in response to salt stress, suggesting its pivotal role in mediating salt stress responses. The GmBASS2-2 gene was cloned and overexpressed in soybean hair roots and Saccharomyces cerevisiae. We found the GmBASS2-2 overexpressing Saccharomyces cerevisiae grew better than the control (pYES3 empty vector) under salt stress. The transgenic soybean plants overexpressing the GmBASS2-2 gene demonstrated superior growth compared to control plants. Gene-based association analysis showed that a total of 2 haplotypes were identified for the GmBASS2-2 gene, and Hap2 haplotype has emerged as a superior allele for enhancing salt tolerance. The above findings suggest that the GmBASS2-2 gene might be involved in the process of soybean tolerance to salt stress. The findings of this study may provide valuable insights into the regulatory mechanisms of GmBASS2-2 in response to salt stress in soybean.

Soybean cyst nematode (SCN, Heterodera glycines) is one of the major pathogens of soybean worldwide. We utilized the CHIP-Seq (chromatin immunoprecipitation sequencing) and RNA-Seq (RNA sequencing) data from the transgenic GmMYB29 strain (Glycine Max roots). We then performed enrichment analysis using KEGG and GO to identify potential candidate genes within the promoter-binding region. A targeted regulatory relationship between the GmMYB29 and GmPP2C-37like genes was further identified using the dual-luciferase Assay (Luciferase, LUC) and yeast one-hybrid Assay (Y1H). Hairy roots with target gene overexpression and gene-edited hairy roots were generated, and their resistance to soybean cyst nematode (SCN) was evaluated. Meanwhile, the presence of reciprocal genes with GmPP2C-37like was determined by the yeast two-hybrid library screening method. The targeting relationship between GmMYB29 and GmPP2C-37like genes was further validated through the Y1H assay and LUC assay. Based on phenotypic assessments of SCN, transgenic soybean roots overexpressing GmPP2C-37like exhibited significantly enhanced resistance to SCN 3 compared to wild-type. Further analysis revealed that GmPP2C-37like collaborates with other regulatory factors to modulate soybean resistance against SCN. Yeast two-hybrid library (Y2H) screening identified 18 interacting proteins. These findings not only illuminate the functional role of GmPP2C-37like but also provide a foundation for dissecting its molecular network. Moreover, the results offer promising candidate genes for enhancing SCN resistance and optimizing soybean resilience through targeted genetic strategies.

Soybean (Glycine max) is a globally important grain and oil crop, but its yield and quality are severely limited by soybean cyst nematode (SCN, Heterodera glycines Ichinohe), a devastating soil-borne pathogen. Here, we evaluated SCN race 3 resistance in 306 soybean germplasms and combined a genome-wide association study (GWAS) with transcriptome analysis to identify key resistance-related genes. GWAS using 30× resequencing data (632,540 SNPs) revealed 77 significant quantitative trait loci (QTLs) associated with SCN resistance, while transcriptome comparison between the extreme resistant accession Dongnong L10 and susceptible Heinong 37 identified 4185 upregulated and 3195 downregulated genes. Integrating these results, we characterized the GmRF2-like gene as a candidate resistance gene. Subcellular localization showed GmRF2-like encodes a nuclear-localized protein. Functional validation via soybean hairy root transformation demonstrated that overexpression of GmRF2-like significantly inhibits SCN race 3 infection. Collectively, our findings confirm that GmRF2-like plays a positive role in soybean resistance to SCN race 3, providing critical insights for dissecting the molecular mechanism of SCN resistance and facilitating the development of resistant soybean varieties.

Seed weight is an important agronomic trait that is related to seed size and determines yield in soybean (Glycine max). We previously identified a spontaneous soybean mutant with light green leaves called ygl2. Here, we cloned YGL2, which encodes a phytochromobilin (PΦB) synthase involved in synthesizing the chromophore of the photoreceptor phytochrome. The lesion in ygl2 is a 10-bp deletion, causing a frameshift mutation and a premature stop codon that truncates the encoded protein. In contrast to the wild type, ygl2 lacks PΦB synthase activity and function. This appears to promote cell expansion, thus increasing seed weight. Surprisingly, the ygl2 mutant also exhibits excellent traits including early maturity and high protein content. Moreover, under the condition of dense planting (3 cm), the yield of YGL2 mutant was significantly increased. Mutants harboring ygl2 mutations that we generated via gene editing had enlarged seeds with high protein content. Moreover, the expression levels of the photoperiod sensitive genes (E1, FT2a, FT5a) were lower in the ygl2 mutant than in the wild type. Mutating the YGL2 gene resulted in increased biliverdin content and decreased heme content. We determined that Lhcb4, a chlorophyll a/b binding protein in photosystem II, interacts with YGL2 but not with the mutant version of the protein. We thus identified a mutation in a PΦB synthase gene that enhances seed weight in soybean, providing a promising breeding target for this important crop.

Soybean cyst nematode (SCN, Heterodera glycines) is a major pathogen harmful to soybean all over the world, causing huge yield loss every year. Soybean resistance to SCN is a complex quantitative trait controlled by a small number of major genes (rhg1 and Rhg4) and multiple micro-effect genes. Therefore, the continuous identification of new resistant lines and genes is needed for the sustainable development of global soybean production. Here, a novel disease-resistance quantitative trait locus Rscn-16 was identified and fine mapped to an 8.4-kb interval on chromosome 16 using an F2 population. According to transcriptome and metabolome analysis, a UDP-glucosyltransferase encoding gene, GmUGT88A1, was identified as the most likely gene of Rscn-16. Soybean lines overexpressing GmUGT88A1 exhibited increased resistance to SCN, higher isoflavone glycosides and larger seed size while the phenotype of RNA-interference and knockout soybean lines showed sensitivity to SCN and decreased in seed size compared to wild-type plants. GmMYB29 gene could bind to the promoter of GmUGT88A1 and coordinate with GmUGT88A1 to regulate soybean resistance to SCN and isoflavone accumulation. Under SCN infection, GmUGT88A1 participated in the reorientation of isoflavone biosynthetic metabolic flow and the accumulation of isoflavone glycosides, thus protecting soybean from SCN stress. GmUGT88A1 was found to control soybean seed size by affecting transcription abundance of GmSWEET10b and GmFAD3C, which are known to control soybean seed weight. Our findings provide insights into the regulation of SCN resistance, isoflavone content and seed size through metabolic flux redirection, and offer a potential means for soybean improvement.

Saline–alkali environments restrict soybean production in China. Wild soybean genes can be used to improve the alkaline tolerance of cultivated soybean in molecular breeding. The expansin protein family promotes cell wall expansion. In this study, the relative expression levels of expansin family genes in wild soybean treated with 50 mM NaHCO3 were measured at 0, 3, 6, and 12 h, and the relative expression of GsEXPA8 was found to be higher at 12 h. Wild soybean was treated with abscisic acid (ABA), indole-3-acetic acid (IAA), gibberellic acid (GA), and jasmonic acid (JA), and GsEXPA8 was found to respond to ABA and IAA signals. Sequence analysis shows that GsEXPA8 has DPBB_EXPA and expansin domains. Subcellular localization analysis shows that GsEXPA8 was localized in the cytoplasm in protoplasts and the cell membrane or wall in tobacco, indicating that it has nuclear membrane localization signals. GsEXPA8 overexpression reduced the malondialdehyde content in transgenic plants treated with NaHCO3 and increased peroxidase activity before treatment. After the transformation of soybean roots from hair roots, GsEXPA8 was found to be expressed in the outer root cells and promote the development of thicker, shorter roots, thereby improving the plant’s alkaline tolerance. Stable GsEXPA8 transformation improved saline alkaline tolerance via the regulation of the alkali stress-related genes GmKIN1, GmRD22, GmDnaJA6, GmNFYC1, and GmMYB14. These findings provide support for further research on alkali-tolerance regulation pathways and molecular breeding for alkali tolerance.

In recent years, single nucleotide polymorphisms (SNP) have emerged as the preferred molecular markers for elucidating the genetic basis of crop-related traits. This preference is attributed to their advantages, including dense distribution across genomes, low mutation rates, and compatibility with automated sequencing technologies, which have significantly advanced genomic sequencing and genotyping capabilities. Identifying phenotypic formation genes independently of a reference genome can accelerate soybean improvement breeding. Traditional breeding methods predominantly rely on phenotypic selection, which involves screening based on observable external characteristics such as plant morphology, yield, and resistance. However, this approach is characterized by a long cycle, low efficiency, and susceptibility to environmental interference. In contrast, molecular marker-assisted selection (MAS) leverages the close linkage between molecular markers and genes that determine target traits. By detecting these markers, the presence of target genes can be inferred, thereby achieving the selection of desired traits and markedly enhancing breeding efficiency. The advent of high-throughput sequencing technology has facilitated the development of various efficient gene localization strategies. For instance, methods based on bulked segregant analysis (BSA), such as QTL-seq, Gradient-Seq, QTG-Seq, exome QTL-seq, and RapMap, compare genomic differences in populations with extreme phenotypes to rapidly identify candidate genes. Mutant-based approaches, including MutMap, NIKS algorithm, MutRenSeq, and MutChromSeq, integrate mutagenesis populations with sequencing technology to pinpoint functional genes. Additionally, techniques utilizing target sequence enrichment, such as RenSeq, AgRenSeq, and TACCA, enable efficient screening of SNPs associated with disease resistance. Furthermore, advancements in statistical methodologies, such as mixed linear models (MLM), multi-site genome-wide association studies (GWAS), and machine learning algorithms, have substantially improved the accuracy and efficiency of classical localization strategies and genome-wide association analyses. These innovations allow for more precise identification of micro-effect polygenic variations and rare alleles linked to complex traits, such as yield and stress resistance. To comprehensively review the progress of SNP marker applications in soybean breeding, this paper summarizes research achievements in 2024 regarding QTL localization and candidate gene function analysis for traits such as yield, quality, stress resistance, and plant architecture, aiming to facilitate the application of more effective SNP loci in molecular marker-assisted breeding.

Vitamin E, comprising tocopherols and tocotrienols, is a crucial fat-soluble antioxidant that helps maintain intracellular redox homeostasis in plants when they are under stress. Soybeans are a significant source of natural vitamin E. GGDR catalyzes the formation of phytyl diphosphate (PDP), a key vitamin E precursor, and it is involved in chlorophyll degradation. The GmGGDR gene, identified via RNA-seq in soybean germplasms with high and low vitamin E contents, encodes GGDR, a key enzyme involved in both vitamin E synthesis and chlorophyll degradation. This study shows that the GmGGDR-encoded protein is hydrophilic and stable, predominantly expressed in leaves, and markedly responsive to gibberellins. The GmGGDR gene enhances the tolerance of transgenic Arabidopsis and soybean plants to salt and drought stresses; transgenic soybeans overexpressing GmGGDR exhibited an approximately 8-fold increase in POD activity, with no significant changes in SOD and CAT activities. Moreover, the GmGGDR gene enhances the levels of α-, γ-, δ-, and total tocopherol content in transgenic soybean and Arabidopsis plants and also increases the chlorophyll a levels in the leaves of these transgenic plants. The increases in α-tocopherol, γ-tocopherol, and δ-tocopherol and total tocopherol in transgenic Arabidopsis seeds ranged from 177.8% to 600.0%, 42.9% to 90.0%, 17.6% to 292.9%, and 71.4% to 127.3% over the control, respectively. Similarly, transgenic soybeans exhibited a minimum increase of 42.9%, 27.8%, 7.1%, and 25.0% in these tocopherol fractions. Overexpression of GmGGDR also significantly elevated chlorophyll a levels in the leaves of these transgenic plants by 33.3–112.5%. This study preliminarily elucidated the function of the GmGGDR gene. It provides a theoretical foundation for further research. It presents a novel strategy for the genetic enhancement of soybean vitamin E content.