Molecular Pathogens, 2025, Vol.16, No.4, 182-192 http://microbescipublisher.com/index.php/mp 183 In recent years, with the development of genome sequencing, high-throughput omics and molecular marking technologies, researchers have made important progress in the genetic basis and molecular mechanism of grape anti-downic mildew disease, identified multiple disease-resistant QTLs and resistance genes, providing gene resources and technical support for targeted cultivation of disease-resistant varieties (Fröbel et al., 2019). Based on the above background, this study comprehensively discusses the pathogen and epidemic, genetic basis of biological resistance, molecular immune mechanism, multiomic analysis, typical germplasm comparison, and molecular breeding practice, etc., based on the above background. 2 The Etiology and Prevalence Characteristics of Grape Downy mildew 2.1 Life cycle and infection process of Plasmoparaviticola The downy mildew of grapes, P. viticola genus Oomycetes, is an obligate parasitic pathogen of grapes. Its life history includes two parts: sexual and asexual stages: sexual spores produced in the host are called oospores, which can overwinter and survive in sick bodies or soil for a long time (Delbac et al., 2019; Bitencourt et al., 2021); in the spring of the following year, oospores germinate under suitable conditions to produce zoospores and release zoospores. Zopores have flagella, which can swim in a directional direction in the water membrane to the stomata of grape leaves or young fruits. After losing the flagella, it forms attached spores and invades the host tissue (Koledenkova et al., 2022). Pathogens form suction devices in host cells, thereby absorbing nutrients and expanding mycelium. After the latent stage, sporophys and sporophys can grow again on the back of the lesions (the back of the leaves). These asexual sporophys release new zoospores under wet conditions and spread, causing repeated infection. At the end of the growing season or when host tissue dies, bacteria induce thick-walled oospores that are deposited in fallen leaves and soil overwinter, preparing inoculation sources for early in the next season (Cesarini et al., 2025). 2.2 The impact of environmental factors on disease occurrence The occurrence and development of grape downy mildew is closely related to environmental conditions. Temperature and humidity are key ecological factors that affect the prevalence of downy mildew: generally, under a warm environment of 18 °C~25 °C and a continuous foliar humid condition with a relative humidity of more than 80%, it is most conducive to sporangia formation and zoospore release, thereby causing serious infection. Rainfall or foliar water film is one of the necessary conditions for the initial infection and secondary transmission of downy mildew. Studies have shown that rain-wearing cultivation can significantly reduce the density and disease intensity of downy mildew sporangia in the air, that is, reducing free water on the foliar surface can inhibit the production and invasion of zoospores. However, in field practice, downy mildew outbreaks in years with frequent natural rainfall are often not completely avoided, and comprehensive prevention and control measures are required (Cesarini et al., 2025). Climate differences in different regions and years lead to changes in the degree of downy mildew. For example, in a typical wet vineyard, if it rains for days or condensation at night for more than 4 hours, the disease may be affected. In addition to climate, cultivation methods can also affect disease prevalence: densely planted and poorly ventilated gardens are more likely to accumulate and spread bacterial sporangia, while strengthening pruning to improve ventilation and light transmission can reduce foliar humidity and reduce disease occurrence (Koledenkova et al., 2022). In addition, removing sick bodies such as fallen leaves and turning deep into the soil in early spring can reduce the number of oospores overwintering, thereby reducing the risk of initial infection. 2.3 Typical popular case analysis Due to the vast grape planting area, the pathogenicity of downy mildew bacterial flora may vary in different regions. In recent years, Chinese scholars have conducted pathogenic differentiation research on regional downy mildew bacteria and achieved meaningful results. Wu et al. (2025) conducted monospore isolation and inoculation identification of downy mildew strains isolated from different vineyards in Ningxia. The results showed that the pathogenicity of these strains was significantly differentiated, and different strains showed different pathogenic types for the grape varieties for testing (Wu et al., 2025). Some strains can cause symptoms in high-resistant varieties, indicating that there is a certain diversity of variants in the downy mildew bacteria population (Figure 1).
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