Legume Genomics and Genetics 2024, Vol.15, No.5, 257-269 http://cropscipublisher.com/index.php/lgg 265 drought conditions (Fatema et al., 2023). Additionally, the use of recombinant inbred line (RIL) populations has facilitated the mapping of QTLs for drought tolerance, providing a robust framework for evaluating and selecting drought-tolerant genotypes in the field (Ren et al., 2020; Dhungana et al., 2021). Environmental variability poses a significant challenge in breeding for drought tolerance, as genotype-environment interactions can influence the expression of drought-related traits. To address this, breeding programs must consider the diverse environmental conditions under which soybeans are grown. Strategies such as multi-environment trials and the use of stress management practices (e.g., optimized irrigation and soil management) are crucial for accurately assessing the drought tolerance of soybean genotypes (Tuberosa and Salv, 2006; Toum et al., 2021). Moreover, understanding the molecular and physiological responses of soybeans to drought stress can inform the development of more resilient varieties capable of withstanding variable environmental conditions (Manavalan et al., 2009; Aleem et al., 2020). By integrating traditional and modern breeding approaches, conducting rigorous field trials, and considering environmental variability, breeding programs can develop soybean varieties with enhanced drought tolerance, ensuring stable yields and food security in the face of climate change. 7 Future Directions and Challenges 7.1 Emerging research areas Recent studies have identified several novel genes and pathways that play crucial roles in drought tolerance in soybeans. For instance, the GmWRKY54 gene has been shown to enhance drought tolerance by activating genes in the ABA and Ca2 + signaling pathways, which are critical for stomatal closure and water retention (Wei et al., 2019). Additionally, the identification of differentially expressed genes (DEGs) in drought-tolerant and sensitive soybean genotypes has revealed key pathways such as auxin transport, cell wall/membrane integrity, and antioxidant activity that are vital for drought response (Aleem et al., 2020; Xuan et al., 2022). Future research should focus on the functional validation of these candidate genes and pathways to develop drought-resistant soybean varieties. Epigenetic regulation and stress memory are emerging as significant areas of research in plant stress tolerance. Epigenetic modifications, such as DNA methylation and histone modifications, can influence gene expression in response to environmental stresses. Studies have shown that epigenetic changes can lead to stress memory, where plants “remember” previous stress exposures and respond more effectively to subsequent stresses. Investigating the role of epigenetic regulation in soybean drought tolerance could provide new insights into developing crops with enhanced stress resilience (Dubey et al., 2019; Wang et al., 2022). 7.2 Challenges in research and application One of the primary challenges in drought tolerance research is translating laboratory findings into practical applications in the field. While numerous genes and pathways have been identified as crucial for drought tolerance, their practical implementation in breeding programs remains a challenge. For example, the overexpression of GmNFYB17 has been shown to enhance drought resistance and yield in transgenic soybeans, but translating these findings into commercial varieties requires extensive field trials and regulatory approvals (Sun et al., 2022). Additionally, the use of CRISPR/Cas9 technology to edit genes like GmHdz4 has shown promise in enhancing drought tolerance, but the regulatory landscape for gene-edited crops is still evolving (Zhong et al., 2022). The development and adoption of drought-tolerant soybean varieties are also influenced by socioeconomic and regulatory factors. Farmers need access to affordable and high-yielding drought-tolerant seeds, and there must be adequate support for the adoption of new technologies. Regulatory frameworks for genetically modified and gene-edited crops vary across regions, which can impact the commercialization of drought-tolerant soybean varieties. Addressing these challenges requires a collaborative approach involving researchers, policymakers, and stakeholders to ensure that scientific advancements translate into tangible benefits for farmers and contribute to global food security (Li et al., 2013; Dubey et al., 2019).
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