Nutrient content of grass influences microbial communities in the phyllosphere more than climate change

Phyllosphere microbes survive in an open and complex environment. Previous studies have characterized seasonal changes in host nutrient content as key factors affecting the balance of colonized phyllosphere microbial communities (PMCs). Meanwhile, climate factors (such as temperature and precipitation) could also influence plant growth and the composition of PMCs. However, the interacting effects of climate factors and seasonal variations in nutritional components on PMCs remain poorly understood. By comparing the partial correlation of climate factors and nutrient contents of grass with PMCs, we found that changes in the crude fiber (CF) content of grasses were negatively correlated with the archaeal community diversity. Conversely, the crude protein (CP) content in grasses was negatively correlated with both the richness and diversity of the fungal community (Pearson's test, p < 0.05). The redundancy analysis (RDA) and multiple regression on (dis)similarity matrices (MRM) further confirmed that the content of CF was the primary factor influencing the distribution of the archaeal community, and CF content also significantly affected the distribution of the fungal community (Spearman's test, p < 0.05). The Mantel test and regression analysis revealed a positive correlation between changes in CF and NDF content and the nearest taxon index (NTI). These findings suggest that changes in nutrient component content have a stronger effect on archaeal and fungal communities than on bacterial communities within PMCs, reflecting a more stable state of bacterial communities. This study demonstrated that the grass nutrient content plays a crucial role in dynamically shaping phyllosphere microbial communities. KEY POINTS: • The changes in grass nutrient content significantly affected the structures and assembly of phyllosphere microbial community (PMCs) compared to the impact of climate change on PMCs. • The contents of CF and CP were significantly correlated with the alpha diversity and community composition of archaea and fungi. • Deterministic processes with heterogeneous selection governed the archaeal community.