International Journal of Molecular Evolution and Biodiversity, 2025, Vol.15, No.2, 84-98 http://ecoevopublisher.com/index.php/ijmeb 89 traits such as root morphology, leaf curling and proline accumulation, some strains have shown significant improvements in water use efficiency and stress tolerance (Ranjith and Rao, 2021). Despite the effectiveness, traditional methods still have significant limitations. On the one hand, the entire breeding cycle often takes many years and requires a large amount of manpower; on the other hand, the genetic resources relied on are limited by the range of variation of the species itself, and it is not easy to achieve significant breakthroughs (Ashraf, 2010). More importantly, drought stress does not have a single effect, but ultimately suppresses yield potential by affecting leaf expansion, stem growth, root distribution and other pathways (Begna, 2022). Coupled with the complex interaction between genetic background and environmental conditions, breeding results are often difficult to maintain consistency under different ecological conditions (Ashraf, 2010). Despite this, conventional breeding is still the basic pillar of drought resistance improvement, especially when combined with modern methods such as molecular assistance, it can play an important role under the premise of clear selection direction. 5.2 Gene marker-assisted selection (MAS) Marker-assisted selection (MAS), as an important means of molecular breeding, has been widely used to improve the adaptability of rapeseed to drought environments. This method relies on molecular markers that are closely linked to the target quantitative trait loci (QTLs), which can achieve early screening of individuals before the trait is expressed (Ashraf, 2010). Compared with traditional breeding methods, MAS significantly shortens the breeding cycle and reduces the dependence on large-scale field trials to a certain extent. In past studies, scientists have mapped several QTL maps related to drought resistance, which cover multiple key indicators such as root growth depth, osmotic regulation ability, and antioxidant enzyme activity (Cattivelli et al., 2008). These traits play an important role in improving the adaptability of rapeseed to drought stress. However, the performance differences of different genotypes in a changing environment, especially the interaction effect between genes and the environment, often affect the stability and positioning accuracy of QTLs, which brings certain challenges to practical applications. Molecular marker-assisted selection (MAS) provides a precise technical means for drought-resistant breeding. By aggregating multiple drought-resistant gene loci, this technology can achieve the coordinated improvement of important traits and effectively improve the adaptability of rapeseed under drought conditions (Ashraf, 2010). With the advancement of molecular marker development technology, MAS is gradually becoming an important strategy for breeding drought-resistant varieties. 5.3 Integrated application of genomic selection and high-throughput phenotyping Genomic selection (GS) represents the innovative direction of modern breeding technology. This method integrates whole genome marker information and phenotypic data to construct a predictive model to evaluate the drought resistance potential of breeding materials (Cattivelli et al., 2008). Compared with MAS, GS can more comprehensively analyze the genetic basis of complex quantitative traits and significantly improve the accuracy and stability of selection. The rise of high-throughput phenotyping (HTP) provides a data basis for the efficient implementation of GS. With the help of remote sensing imaging, multispectral analysis and automation platforms, researchers can collect important trait data such as stomatal conductance, chlorophyll content and root morphology of crops under drought stress in a short period of time (Cattivelli et al., 2008; Wu et al., 2018). These high-resolution phenotypic information not only enriches the input variables of the prediction model, but also improves the depth of analysis of the interaction between genotype and environment. The synergistic integration of high-throughput phenomics (HTP) and genomic selection (GS) has significantly improved the efficiency of drought-resistant breeding. This multi-omics strategy has achieved a significant shortening of the breeding cycle and a significant improvement in selection accuracy by optimizing the genotype screening process, providing technical support for the breeding of rapeseed varieties with stronger adaptability.
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