Community assembly and biogeography of plant-associated microbes

Unraveling the factors that shape microbial communities is a crucial pursuit in microbial ecology. However, our understanding of leaf-associated bacteria has been predominantly derived from studies conducted at small spatial scales, leaving us with limited knowledge about the geographic patterns and drivers that influence leaf-bacteria associations.

Based on a biogeographic survey of leaf bacteria on 329 tree species across 10 forest sites along a broad latitudinal gradient in China (thanks to many collaborators), we for the first time provided quantitative and process-oriented understanding on the biogeography of leaf-associated bacteria.

We found that, similar to macroorganisms, leaf bacteria exhibit biogeographic patterns, with diversity and composition varying across latitudes. These patterns are likely driven by the selective forces imposed by hosts and climates, while dispersal limitation appears to play a less significant role.

Additionally, our investigation revealed that leaf bacteria specializing in specific hosts tend to possess smaller genome sizes and lower GC content compared to host-generalized bacteria, indicative of genome streamlining in host specialization.

Furthermore, we discovered that bacteria associated with locally abundant host species exhibit wider distribution ranges and lower levels of host specialization compared to those associated with rare host species. This implies that bacterial horizontal transmission may hinder the development of host specialization.