Genetic diversity of diazotrophs and total bacteria in the phyllosphere of , , , and .

The phyllosphere, which supports a large number of microorganisms, represents the interface between the aboveground parts of plants and air. In this study, four clone libraries were constructed from the phyllosphere of (L), (P), (X), and (Y). Clones related to (L, 12.1%; X, 15.6%; Y, 62.5%; P 70.8%), (X, 2.1%; P, 15.1%; L, 63.7%), (X, 68.8%), (L, 3.3%; P, 7.6%), and (P, 0.9%; L, 4.4%, X; 5.2%, Y; 19.6%) were present at high percentages, highlighting their critical role in contributing nitrogen to the phyllosphere ecosystem. The 16S rDNA sequence analysis suggested that phyllosphere-associated bacteria were affiliated with a wide range of taxa, encompassing members from , , , , , , , , , and -. Additionally, the abundance of the gene and 16S rDNA was assessed with quantitative PCR. The number of copies of and 16S rDNA ranged from 1.14 × 10 to 1.49 × 10 and from 3.72 × 10 to 7.02 × 10 copies/g fresh leaf sample, respectively. In conclusion, our work sheds light on the microbial communities of the phyllosphere that are important for plant growth. Moreover, we observed a unique composition of nitrogen-fixing bacteria in each phyllosphere sample, suggesting the existence of specific interactions between these functional microorganism and plants, which may provide information or be a reference for the development of bacterial fertilizers.