Molecular Plant Breeding 2025, Vol.16, No.3, 165-179 http://genbreedpublisher.com/index.php/mpb 173 rapid and accurate development of drought-resistant varieties. Recently, Zhang et al. (2023) analyzed 459 rice varieties and found that the reproducing kernel Hilbert space (RKHS) model had the highest predictive accuracy for drought tolerance. By integrating GS with GWAS, they enhanced GS application, significantly improving the precision and efficiency of breeding drought-resistant rice varieties. Similarly, Wang et al. (2024) conducted a comprehensive study integrating genome, transcriptome, and population analyses of rice, identifying key candidate genes for drought adaptation in upland rice. They developed a genomic navigation map for drought-resistant rice breeding, highlighting the pivotal role of highland-specific variations in improving drought tolerance. 7 Prospects and Challenges in Breeding Drought-resistant Rice 7.1 Integrating molecular and breeding approaches Breeding drought-resistant rice is a multifaceted challenge that requires the integration of various scientific disciplines and methodologies. This section explores the prospects and challenges in this field, focusing on integrating molecular and breeding approaches, the potential and limitations of current techniques, and future directions and innovations. The integration of molecular genetics with traditional breeding methods holds significant promise for developing drought-resistant rice varieties. Molecular markers linked to drought resistance traits, such as root characteristics and osmotic adjustment, have been identified and are being used in MAS (Oladosu et al., 2019). For example, QTLs associated with root architecture, such as Deeper Rooting 1 (DRO1), have been incorporated into elite rice cultivars, enhancing drought tolerance by promoting water uptake from deeper soil layers (Uga et al., 2013). The development of molecular linkage maps and the identification of QTLs associated with drought resistance traits have provided new tools for breeders. Transgenic approaches, including the introduction of genes responsible for osmoprotectants like proline and glycine betaine, have shown potential in enhancing drought tolerance (Hadiarto and Tran, 2011). However, the success of these approaches depends on close collaboration between molecular geneticists, plant physiologists, and breeders to ensure the practical application of these genetic tools in breeding programs. The challenge lies in combining these advanced technologies with field-based breeding practices to ensure that drought-resistant varieties perform well in farmers’ fields under real-world conditions. 7.2 Potential and limitations of current techniques Current techniques in breeding drought-resistant rice include conventional breeding, MAS, and genetic engineering. Conventional breeding has been foundational in the development of drought-resistant varieties, but it is often slow and resource-intensive due to the low heritability of yield under stress and environmental variability (Panda et al., 2021). Despite these limitations, conventional breeding remains essential for selecting traits from landraces and wild rice varieties that have naturally adapted to drought-prone environments. MAS offers a more efficient alternative by allowing the selection of specific traits linked to drought resistance, but it still requires extensive field testing to confirm the effectiveness of selected markers. Additionally, many QTLs associated with drought tolerance have only small effects, necessitating the combination of multiple QTLs to achieve significant improvements in yield stability under drought (Bernier et al., 2007). Genetic engineering provides a direct approach to introducing drought-resistant genes, but it faces regulatory hurdles and public acceptance issues (Hadiarto and Tran, 2011; Hu and Xiong, 2014). Additionally, the complexity of drought resistance, which involves multiple genes and environmental interactions, poses a significant challenge to all these techniques (Sahebi et al., 2018). 7.3 Future directions and innovations Future research in breeding drought resistant rice should focus on a multidisciplinary approach, integrating advanced genetic techniques, precise phenotyping, and an understanding of plant physiology under drought conditions (Sahebi et al., 2018). Emerging innovations like high-throughput phenotyping, genome editing technologies like CRISPR/Cas9, and systems biology approaches can provide deeper insights into the molecular mechanisms of drought resistance and identify new targets for breeding (Price et al., 2002; Sircar and Parekh, 2019). Systems biology approaches, combining transcriptomics, proteomics, and metabolomics, can offer comprehensive insights into the molecular mechanisms governing drought responses, enabling researchers to
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