Abiotic environments prevail over plant functional traits in shaping phyllosphere fungal communities of temperate grasslands in China

Phyllosphere fungi play a crucial role in plant health, yet the specific
mechanisms governing their diversity and structure in different leaf
habitats (endophytic and epiphytic) lack systematic comparison.
Additionally, current studies rarely comprehensively consider how abiotic
environments and plant functional traits jointly shape phyllosphere fungal
communities across environmental gradients. We collected 231 leaf samples
from nine sites in temperate grasslands of northern China, and explored
the effect of abiotic environments and plant functional traits on the
diversity and structure of phyllosphere fungi at the regional scale. Our
analysis revealed that aridity, poor soil conditions, and leaf pH
decreased the relative abundance of leaf endophytic saprophytic fungi, and
plants with a ‘fast-growing’ strategy promoted the relative abundance of
phyllosphere pathogenic fungi. The positive effects of aridity and poor
soils on the richness of leaf endophytic fungi were undermined by soil
fungal richness, while the richness and Pielou’s evenness of leaf
epiphytic fungi was inhibited by the availability of soil resources. Soil
organic carbon emerged as a key factor influencing the composition of
phyllosphere fungal communities, and leaf endophytic fungi were subject to
greater dispersal limitation than their epiphytic counterparts. Our
findings demonstrate that abiotic environments prevail over plant
functional traits in shaping phyllosphere fungal communities, offering new
insights into plant-fungi interactions.