Molecular Pathogens, 2025, Vol.16, No.2, 61-68 http://microbescipublisher.com/index.php/mp 62 oil quality. This disease is caused by a fungus that does not specifically attack rapeseed, it can infect many other plants. It spreads in the plant through mycelium and sclerotia, causing the stems to rot and the whole plant to wither. During the infection process, the bacteria release some enzymes that break down the cell wall of the plant, such as polygalacturonase, which makes it more likely to invade plant tissues (Ding et al., 2021). Because there are not many varieties of rapeseed that are resistant to disease, this disease has become a big problem. In order to prevent and treat this disease, genetic improvement and molecular breeding must be used (Zhou, 2024). 2.3 Epidemiological characteristics of black spot (Alternaria spp.) and white rust (Albugo candida) In addition to clubroot disease and sclerotinia stem rot, rapeseed is often affected by black spots and white rust. Black spot disease is caused by Germacoposus, which mainly produces black spots on leaves and stems. The leaves are prone to fall off, affecting photosynthesis and eventually leading to reduced yields (Starosta et al., 2024). The disease can be controlled by screening disease-resistant genes using molecular markers. White rust is caused by Candida albicans, and small white blisters will grow on the diseased leaves and stems, which will also reduce yield. To prevent and treat these two diseases, one method alone cannot be used. Multiple methods must be used together, such as disease-resistant varieties, reasonable rotation, humidity control, etc., to reduce the losses caused by the disease from many aspects. 3 Molecular Basis of Genetic Resistance in Rapeseed 3.1 Classification and mechanisms of plant resistance genes The disease-resistant genes of rape can be roughly divided into two types: one is the main resistance gene (R gene), and the other is the quantitative trait loci (QTL). The R gene can provide strong but more specific disease resistance, but bacteria can often adapt quickly and break through its defenses. By contrast, QTL offers less resistance, but is more stable and more durable (Starosta et al., 2024). Especially when dealing with diseases like black shin, QTL performs better. Some experiments can illustrate how complex the resistance mechanism of rapeseed is. For example, the rapeseed variety ZS11 and its mutant Lmm1 shown in the figure. Lmm1 leaves curl and grow slowly during the seedling and flowering period, which is very different from ZS11. This may be related to the salicylic acid signaling pathway. This pathway is very important for plants and can activate some disease-resistant genes, such as PRs genes, to help plants fight the invasion of pathogens. Lmm1 is also very sensitive to light. When the light is sufficient, it grows slowly; when the light is insufficient, its lesions become more obvious. This shows that light will affect the expression of disease-resistant genes and also affect the health of the plant. The difference in leaf shapes between Lmm1 and ZS11. The leaves of Lmm1 are irregular and sometimes yellow or necrotic spots, indicating that there is a problem with its energy distribution between growth and immunity (Figure 1) (Yu et al., 2023). Figure 1 Phenotypic comparison between ZS11 and ZS Lmm1 (Adopted from Yu et al., 2023) Image caption: (a) The representative images of ZS11 and ZS are Lmm1 plants in the early bolt stage (b) The comparison of factory structures between ZS11 and ZS11 shows that LMM1 is in its infancy stage (c) Lmm1 grows in sunlight (d) Shadow processing Lmm1 one week vacation (e) ZS11 and ZS11 blade surface type Lmm1 in early bolt stage (Adopted from Yu et al., 2023)
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