State Key Laboratory of Grassland Agro-Ecosystems & Institute of Innovation Ecology, Lanzhou University, Lanzhou, 730000, China.
National Observation and Research Station for Yangtze Estuarine Wetland Ecosystems, Ministry of Education Key Laboratory for Biodiversity Science and Ecological Engineering, Institute of Biodiversity Science, School of Life Sciences, Fudan University, Shanghai, 200438, China.
New Phytol. 2021 Oct;232(1):345-355. doi: 10.1111/nph.17324. Epub 2021 Jun 5.
Plant pathogens and their hosts often coexist with mammal grazers. However, the direction and strength of grazing effects on foliar fungal diseases can be idiosyncratic, varying among host plant species and pathogen types. We combined a 6 yr yak-grazing experiment, a clipping experiment simulating different mammal consumption patterns (leaf damage vs whole-leaf removal), and a meta-analysis of 63 comparisons to evaluate how grazing impacts foliar fungal diseases across plant growth types (grass vs forb) and pathogen life histories (biotroph vs necrotroph). In the yak-grazing experiment, grazing had no significant effect on disease severity, and grasses experienced a higher disease severity than forbs; there was a significant interaction between pathogen type and grazing. In both the yak-grazing experiment and meta-analysis, grazing decreased biotrophic pathogens (mainly rusts and powdery mildew), but did not affect necrotrophic pathogens (mainly leaf spots). The clipping experiment suggested that grazers might promote infection by necrotrophic pathogens by producing wounds on leaves, but inhibit biotrophic pathogens via leaf removal. In conclusion, our three-part approach revealed that intrinsic properties of both plants and pathogens shape patterns of disease in natural ecosystems, greatly improving our ability to predict disease severity under mammal grazing.
植物病原体及其宿主通常与哺乳动物食草动物共存。然而，食草动物对叶部真菌病的影响方向和强度可能是特殊的，因宿主植物物种和病原体类型而异。我们结合了一项为期 6 年的牦牛放牧实验、一项模拟不同哺乳动物消费模式（叶片损伤与整叶去除）的剪叶实验，以及对 63 项比较的荟萃分析，评估了放牧如何影响植物生长类型（草本植物与草本植物）和病原体生活史（生物营养型与坏死营养型）的叶部真菌病。在牦牛放牧实验中，放牧对疾病严重度没有显著影响，且草本植物的疾病严重度高于草本植物；病原体类型和放牧之间存在显著的相互作用。在牦牛放牧实验和荟萃分析中，放牧减少了生物营养型病原体（主要是锈病和白粉病），但对坏死营养型病原体（主要是叶斑病）没有影响。剪叶实验表明，食草动物可能通过在叶片上产生伤口来促进坏死营养型病原体的感染，但通过去除叶片来抑制生物营养型病原体。总之，我们的三部分方法揭示了植物和病原体的内在特性塑造了自然生态系统中疾病的模式，极大地提高了我们在哺乳动物放牧下预测疾病严重度的能力。
