Fengzhen Yang ^1,2* Xiaojian Pu ³ Cory Matthew ⁴ Zhibiao Nan ⁴ Xinrong Li ¹

• ¹ Shapotou Desert Research and Experiment Station, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, Gansu Province, China
• ² Lanzhou University, Lanzhou, China
• ³ Qinghai Animal Husbandry and Veterinary College, Xining, Qinghai Province, China
• ⁴ College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, Gansu Province, China

The phyllosphere of plants hosts diverse fungal microbial communities.Despite the significant impact of plant fungal diseases on productivity and community ecology, the relationship between phyllosphere fungal communities and plant health in natural environments remains poorly understood. This study utilized highthroughput sequencing and field investigations to explore the composition, dynamics, and incidence of fungal diseases across 29 plant species from four functional groups (forbs, grasses, legumes, and sedges) in alpine meadow plant communities of the Qinghai-Tibetan Plateau. We identified Ascomycetes and Basidiomycetes as the predominant phyllosphere fungi. Significant differences were observed in the Shannon diversity index, β-diversity, indicator fungi, and hub fungi among the functional groups. With the exception of the sedge group, the incidence of fungal diseases in other groups was positively correlated with the proportion of pathogens in the phyllosphere fungal community. Predictive analyses revealed that Ascochyta was strongly associated with high disease incidence in grasses, Cercospora in forbs, and Podosphaera in legumes, while Calophoma was associated with low disease incidence in sedges. These findings enhance our understanding of how plant phyllosphere fungal communities assemble in natural environments and improve our ability to predict and manage foliar fungal diseases in alpine meadows.