The soybean is a significant legume crop, providing several vital dietary components. Extreme heat stress negatively affects soybean yield and quality, especially at the germination stage. Continuous change in climatic conditions is threatening the global food supply and food security. Therefore, it is a critical need of time to develop heat-tolerant soybean genotypes. Different molecular techniques have been developed to improve heat stress tolerance in soybean, but until now complete genetic mechanism of soybean is not fully understood. Various molecular methods, like quantitative trait loci (QTL) mapping, genetic engineering, transcription factors (TFs), transcriptome, and clustered regularly interspaced short palindromic repeats (CRISPR), are employed to incorporate heat tolerance in soybean under the extreme conditions of heat stress. These molecular techniques have significantly improved heat stress tolerance in soybean. Besides this, we can also use specific classical breeding approaches and different hormones to reduce the harmful consequences of heat waves on soybean. In future, integrated use of these molecular tools would bring significant results in developing heat tolerance in soybean. In the current review, we have presented a detailed overview of the improvement of heat tolerance in soybean and highlighted future prospective. Further studies are required to investigate different genetic factors governing the heat stress response in soybean. This information would be helpful for future studies focusing on improving heat tolerance in soybean.

Abiotic stresses and climate changes cause severe loss of yield and quality of crops and reduce the production area worldwide. Flooding stress curtails soybean growth, yield, and quality and ultimately threatens the global food supply chain. Flooding tolerance is a multigenic trait. Tremendous research in molecular breeding explored the potential genomic regions governing flood tolerance in soybean. The most robust way to develop flooding tolerance in soybean is by using molecular methods, including quantitative trait loci (QTL) mapping, identification of transcriptomes, transcription factor analysis, CRISPR/Cas9, and to some extent, genome-wide association studies (GWAS), and multi-omics techniques. These powerful molecular tools have deepened our knowledge about the molecular mechanism of flooding stress tolerance. Besides all this, using conventional breeding methods (hybridization, introduction, and backcrossing) and other agronomic practices is also helpful in combating the rising flooding threats to the soybean crop. The current review aims to summarize recent advancements in breeding flood-tolerant soybean, mainly by using molecular and conventional tools and their prospects. This updated picture will be a treasure trove for future researchers to comprehend the foundation of flooding tolerance in soybean and cover the given research gaps to develop tolerant soybean cultivars able to sustain growth under extreme climatic changes.

Soil salinization is a major global challenge that limits crop productivity by inhibiting plant growth, nutritional quality and decreasing yields. This study examined the effect of foliar application of molybdenum (Mo) on two soybean varieties, HN517 (salt-sensitive) and DS118 (salt-tolerant) under saline-alkali soil conditions. Mo was applied via foliar spraying at four concentrations 0 (control), 70, 140, and 210 g ha−1 referred as CK, MO1, MO2, and MO3, respectively. These treatments were employed to investigate the influence of Mo on soybean physiological growth parameters, antioxidant defense mechanisms, osmotic regulation, ionic homeostasis, and nutrient accumulation. Results showed that foliar application of Mo treatment MO3 significantly improved plant height, root biomass, and total biomass by 39.24%, 43.67%, and 56.01% in HN517, and by 36.95%, 28.98%, and 108.0% in DS118 variety of soybean. The activities of antioxidant enzymes including superoxide dismutase, catalase, peroxidase, and nitrate reductase, increased by 17.75%, 20.90%, 21.42%, and 13.23% in HN517, and by 24.63%, 27.01%, 18.75%, and 13.44% in DS118, respectively, compared with control. Simultaneously, the levels of hydrogen peroxide, superoxide anion, and malondialdehyde decreased by 26.45% and 35.02%, 23.11% and 22.93%, and 33.30% and 38.38% in HN517 and DS118, respectively, indicating a reduction in oxidative damage. Mo application also enhanced osmotic regulation by increasing proline, soluble protein, and soluble sugar contents by 21.47%, 18.75%, and 16.74% in HN517, and by 19.12%, 23.34%, and 19.69% in DS118. Furthermore, Mo enhanced nutrient uptake, including nitrogen, phosphorus, potassium, and Mo in both varieties. It also improved the K⁺/Na⁺ ratio, mitigating ion toxicity and enhancing stress tolerance. This improvement contributed to higher nutrient acquisition and antioxidant capacity contributed to higher protein and oil content, leading to increased crop yield under saline-alkali field conditions. These findings concluded that Mo application to the foliage improves soybean resilience, growth, yield, and nutritional quality of soybean under saline alkali field conditions.

Drought stress is a major limiting factor that adversely affects both the yield and quality of soybean crops. Transcription factors (TFs) play a pivotal role in regulating gene expression, facilitating plant adaptation and response to various abiotic stresses. Among the 179 NAC TFs encoded in the soybean genome, several are differentially expressed under stress conditions; however, the functional role of GmNAC3 in drought tolerance remains largely unknown. In this study, we cloned the 840 bp coding sequence of GmNAC3 and developed transgenic soybean hairy roots via Agrobacterium-mediated transformation to explore its role in drought response. The physiological and molecular responses of GmNAC3 overexpression (OE) chimeric soybean plants were assessed under polyethylene glycol (PEG)-simulated drought stress using Hoagland nutrient solution. Compared to empty vector (EV) controls, OE plants exhibited enhanced drought tolerance, including improved phenotypic traits, better root development, and stress resilience. Notably, OE plants showed a 23.9% reduction in hydrogen peroxide accumulation and a 31.25% decrease in superoxide anion levels. Biomass analysis on MS medium revealed significantly higher fresh and dry weights of OE hairy roots across different mannitol concentrations compared to EV roots. Furthermore, GmNAC3 overexpression led to the upregulation of key downstream genes involved in stress response, particularly GmLAC5 and GmLAC7. These findings suggest that GmNAC3 enhances drought tolerance in soybean by regulating both physiological and molecular pathways. Overall, GmNAC3 represents a promising target for genetic engineering aimed at improving drought resistance in soybean and potentially other crops.

The soybean is one of the most significant legume crops around the globe and serves as a source of dietary components for humans and animals. It has a higher percentage of protein compared to any other crop. Soybean yield and quality have been affected by many environmental factors. The genetic mechanism of yield and quality is still not clearly understood. Hence there is still a need to investigate the major potent factors to shed light on the mechanism behind yield and quality traits in soybean. Recently, a lot of significant work, including novel QTL, genes, and CRISPR-based genome editing in soybeans, has been done, which opened new doors of hope. The current review has presented detailed work done previously. We have also discussed the role of different breeding techniques in the conventional way of soybean improvement. The genetic factors regulating yield, quality, and disease resistance could be further cloned and transferred into elite cultivars to attain higher output in the current situation of changing environment. The integrated use of several techniques, like CRISPR/Cas9, next-generation sequencing, omics approaches, would be a fruitful way to improve soybean yield and quality. Besides this, hybridization, mass selection, pure line selection, backcross breeding, and pedigree selection should be adopted to develop novel soybean cultivars. This review concluded that soybean yield and quality improvement could be enhanced by exploring its genetic mechanism using several molecular and conventional methods.

The soybean is a source of several dietary components, including milk, protein, and oil. Cold stress has significantly curtailed soybean growth and yield in large areas and caused a high risk to global food security. The main objective of soybean breeders is to improve soybean resistance to cold stress. Conventional breeding approaches have made significant progress in developing cold tolerance in soybean; however, the high cost and complex genetic mechanism of cold tolerance hindered the large scale of these techniques. Molecular tools like quantitative trait loci (QTL), genome-wide association studies (GWAS), transcription factors (TFs), genetic engineering, and transcriptome have been used to identify cold tolerant genes/QTL and to develop soybean cultivars tolerant to cold stress. Clustered, regularly interspaced short palindromic repeats (CRISPR/Cas9) is used to increase the abiotic stress tolerance in soybean; however, its use to edit the cold tolerance genes in soybean is limited. Mapping of QTL has accelerated the master-assisted selection (MAS) in soybean. This review presents a detailed overview of molecular techniques and their use in developing cold-tolerant soybean cultivars. Using CRISPR/Cas9 would increase the speed of molecular breeding for cold tolerance in soybean. This information will assist soybean researchers in uncovering the basis of cold stress tolerance in soybean and adopting the most suitable way to breed the cold tolerant cultivars which can thrive under the extreme pressure of cold stress.