As an important habitat for microorganisms, the phyllosphere has a great impact on plant growth and health, and changes in phyllosphere microorganisms are closely related to the occurrence of leaf diseases. However, there remains a limited understanding regarding alterations to the microbial community in the phyllosphere resulting from pathogen infections. Here, we analyzed and compared the differences in phyllosphere microorganisms of powdery mildew cucumber from three disease severity levels (0% < L1 < 30%, 30% ≤ L2 < 50%, L3 ≥ 50%, the number represents the lesion coverage rate of powdery mildew on leaves). There were significant differences in α diversity and community structure of phyllosphere communities under different disease levels. Disease severity altered the community structure of phyllosphere microorganisms, Rosenbergiella, Rickettsia, and Cladosporium accounted for the largest proportion in the L1 disease grade, while Bacillus, Pantoea, Kocuria, and Podosphaera had the highest relative abundance in the L3 disease grade. The co-occurrence network analysis of the phyllosphere microbial community indicated that the phyllosphere bacterial community was most affected by the severity of disease. Our results suggested that with the development of cucumber powdery mildew, the symbiotic relationship between species was broken, and the entire bacterial community tended to compete.

中文翻译：

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白粉病引起的黄瓜叶际微生物群落动态变化

叶际作为微生物的重要栖息地，对植物生长和健康影响很大，叶际微生物的变化与叶部病害的发生密切相关。然而，对于病原体感染引起的叶际微生物群落的改变，人们的了解仍然有限。在此，我们分析比较了黄瓜白粉病3个发病严重级别（0%＜L1＜30%、30%≤L2＜50%、L3≥50%，数字代表病斑）叶际微生物的差异。叶上白粉病的覆盖率）。不同病害水平下叶际群落的α多样性和群落结构存在显着差异。病害严重程度改变了叶际微生物的群落结构，罗森堡菌属、立克次氏体和枝孢菌属在L1病害等级中所占比例最大，而芽孢杆菌属、泛菌属、库库菌属和足球菌属在L3病害等级中相对丰度最高。叶际微生物群落的共现网络分析表明，叶际细菌群落受疾病严重程度的影响最大。我们的结果表明，随着黄瓜白粉病的发展，物种之间的共生关系被打破，整个细菌群落趋于竞争。