Molecular Pathogens, 2025, Vol.16, No.4, 182-192 http://microbescipublisher.com/index.php/mp 190 genotypes were performed on the disease-resistant sites of alternative parents (such as downy mildew and powdery mildew resistance genes such as Rpv10 and Ren3), and materials with multiple resistance alleles were selected as hybrid parents, thus effectively increasing the frequency of occurrence of medium and high-anti-anti-anti-strains in offspring. In addition to MAS, genome selection (GS) has also begun to make its mark on grapes. GS builds a genome-wide marker effect model in a set of data sets with phenotypic assays, and then uses this model to predict its trait value on phenotypic individuals. For the resistance to disease resistance of grapes, GS has the potential to integrate the contribution of a large number of small-effect genes, so it is more comprehensive than MAS (often focusing on a few main-effect genes) (Huang and Feng, 2025). 7.3 Case analysis: practice of molecular labeling in improving downy mice varieties In order to more intuitively demonstrate the role of molecular breeding, breeding of the new downy mildew-resistant wine grape variety "Zixia No. 1" was selected. They selected a European and American hybrid disease-resistant line A (including Rpv7 and Rpv10 resistance sites) to hybridize with a high-quality Eurasian variety B in order to introduce the disease-resistant gene of A into the excellent winemaking background of B. A total of 200 F1 seedlings were obtained through conventional hybridization. If molecular markers are not used, all 200 seedlings need to be planted in the diseased garden for at least two years before they can determine their disease resistance and fruit quality. Now, the leaves of the seedlings are extracted for DNA extraction in the 4th leaf stage, and the previously developed markers linked to Rpv7 and Rpv10 were used for PCR detection. The results showed that among the 200 offspring, about 50 were accompanied by Rpv7 and Rpv10 markers from parent A (conforming to a theoretical 1/4 ratio). These 50 seedlings were transplanted into diseased high-pressure nurseries for downy mildew resistance identification, and the winemaking quality indicators were evaluated after the results. Finally, it was found that two of them had high resistance to downy mildew (naturally infected without lesions) and excellent fruit traits, and the quality of the first brewed wine sample was comparable to that of the parent B (Figure 3). These two plants were further reproduced and entered the variety area trial, and applied for the variety registration and named "Zixia No. 1" three years later (Fröbel et al., 2019; Possamai et al., 2020). Figure 3 Dual-scale classification of symptoms. Sporulation and necrosis were evaluated separately by visual inspection of each leaf disc at 9 days post-inoculation withP. viticola(Adopted from Possamai et al., 2020) In addition to the above artificial hybridization cases, molecular markers can also be used to explore local disease-resistant resources and improve traditional varieties. By evaluating the resistance of an old breed in a place, it was found that the Rpv3 gene was hidden and it was hybridized with another resistance gene source, and then the new materials for double-gene polymerization were screened out using the marker. Acknowledgments The authors would like to thank all teachers and colleagues who provided guidance and assistance during this research, and for the peer review's revision suggestions.
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