Triticeae Genomics and Genetics 2024, Vol.15, No.1, 1-9 http://cropscipublisher.com/index.php/tgg 4 2.2 Application of molecular markers in wheat stress resistance breeding The application of molecular markers in wheat stress resistance breeding is a key and popular technology, which is crucial for improving wheat yield and quality. Wheat is one of the world's major food crops, however, it is often threatened by adverse factors such as drought, high temperature, saline alkali soil, etc. To address these challenges, breeders need to cultivate wheat varieties that are more tolerant to stress, and molecular marker assisted selection (MAS) has become a powerful tool to achieve this goal. Molecular markers can help identify stress resistance genes related to specific stress conditions, which can come from different wheat varieties or wild parents. With the assistance of molecular markers, these genes can be easily introduced into the target variety to improve its stress resistance. MAS allows breeders to select individuals with target stress resistance genes during the breeding process, which can save time and resources and avoid heavy field trials. Therefore, through molecular markers, wheat breeders can more effectively cultivate stress resistant varieties. For example, Puccinia striiformis f. sp. Tritici (Pst) is one of the fungal diseases that cause widespread, prevalent, and severe damage to wheat stripe rust. Searching for new disease resistant resources and cultivating disease resistant varieties is one of the most cost-effective ways to control the spread of wheat stripe rust. The study utilized resistance gene similarity sequence polymorphism (RGAP) markers Xwgp36, Xwgp43, and Xwgp44 for assisted selection to transfer the wheat stripe rust resistance gene Yr39 to Chuanmai 42, Bainong Aikang 58, Han 6172, and Zhengmai 9023. Through field agronomic trait evaluation and disease resistance identification, a group of resistant families with excellent agronomic traits were selected. Through molecular markers, breeders can selectively improve specific traits of wheat, such as drought tolerance, high temperature tolerance, and salt alkali tolerance. This is expected to improve the stress resistance of wheat, thereby increasing yield and quality (Zheng et al., 2022) (Figure 1). Figure 1 Frequency distribution of 71 backcross offspring lines in four hybrid combinations (Zheng et al., 2022) Note: a: Plant height; b: Spike grain number; c: Number of tillers; d: Thousand grain weight
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