Effects of the symbiosis between fungal endophytes and Atractylodes lancea on rhizosphere and phyllosphere microbial communities

Abstract

Tissue-cultured plantlets of Atractylodes lancea were inoculated with the endophytes AL4 (Cunninghamella sp.) and AL12 (Gilmaniella sp.), and subsequently transplanted into soil after hardening of the tissue-cultured plantlets. We investigated rhizospheric and phyllospheric microbial communities using culture-based and culture-independent methods. Energy spectrum analysis, high performance liquid chromatography, and other assay methods were employed to quantify the elements in the leaves, and the soluble sugars, free amino acids and organic acids in the rhizosphere. The results showed that the endophytes enhanced the diversity and size of the rhizospheric microbial populations. In the phyllosphere, AL4 (Cunninghamella sp.) enhanced the diversity and size of bacterial populations, while AL12 (Gilmaniella sp.) enhanced the diversity and size of fungal populations. The dominant bacterial genera were Microbacterium, Kocuria and Sphingomon in the endophytes-inoculated groups, and Acinetobacter and Bacillus in the endophytes-free group. While Acremonium and Curvularia were the dominant fungal genera in the phyllosphere of endophytes-inoculated groups, Fusarium and Penicillum were most common in the endophytes-free group. AL4 (Cunninghamella sp.) enhanced the rhizospheric microbial population size and diversity by increasing rhizospheric free amino acids, while AL12 (Gilmaniella sp.) altered the rhizospheric microbes by changing concentration of soluble sugars in the rhizosphere. Elemental levels in the phyllosphere and the nutrients in the rhizosphere varied among the treatments and may also have influenced the microbial communities.