Pathological Impact on the Phyllosphere Microbiota of Artemisia argyi by Haze.

The pathological impact of haze upon the phyllosphere microbiota waits for exploration. A moderate degree of haze environment, and a clean control, was recruited in Chengdu, China. Artemisia argyi, a ubiquitously disturbed and extensively applied Chinese herb, was chosen. Total genome DNA from leaf samples was extracted. For metagenome sequencing, an Illumina HiSeq 2500 platform was applied. Results displayed that gene numbers of phyllosphere microbiota derived from haze leaves were less than those of clean control. Both phyllosphere microbiota derived from haze and clean group share the same top ten phylum; the abundance of Proteobacteria, Actinomycetes and Anorthococcuso of the haze group were substantially increased, while Ascomycetes and Basidiomycetes decreased. At the genus level, the abundances of Nocardia, Paracoccus, Marmoricola and Knoelia from haze leaves were markedly increased, while the yeasts were statistically decreased. KEGG retrieval demonstrated that the functional genes were most annotated to metabolism. An interesting find of this work is that the phyllosphere microbiota responsible for the synthesis of primary and secondary metabolites in artemisia argyi were significantly increased under haze environment. Relatively enriched genes annotated by eggNOG belong to replication, recombination and repairment, and genes classified in glycoside hydrolase and glycosyltransferase were significantly increased. In summary, the structure and function of phyllosphere microbiota was globally impacted by haze, primary and secondary metabolites responsible for haze tolerance were considerably increased. Which suggests an adaptive strategy for the tolerance confronting haze damage.