Dominant microbial community in rhizosphere affecting active components of Cinnamomum migao at different ripening stages and their response to soil properties

Objectives Microbial diversity affects the main fruit ingredients that determine the fruit medical quality of Cinnamomum migao. We compared the microbial communities in the rhizosphere of C. migao at different ripening stages, and their relationship with soil chemical and biological properties.

Methods This study was conducted at three typical sites Luodian (LD), Bapeng (BP) and Xiangle (XL) known for growing of C. migao in Guizhou Province, China. At young, nearly maturing and maturing stages, we collected C. migao fruit samples for determination of main medical ingredients, and rhizosphere soil samples for measurement of microorganisms and chemical and biological properties.

Results A total of 870008 effective fungal sequences (belonging to 3026 OTUs) and 568739 effective bacterial sequences (belonging to 4971 OTUs) were obtained from the three sites. The dominant rhizosphere fungus genus at young fruit stage were Saitozyma and Mortierella, at close to mature period were Ganoderma and Clitocybula, and at mature period were Mortierella and Saitozym. The rhizosphere bacteria were Sphingomonas and Arthrobacter at young fruit periods, Arthrobacter and Bacillus were higher in close to mature periods, and Arthrobacter and Acidibacter were higher in mature period. The results showed that the fruit had high contents of sugar and crude fat and moderate volatile oil content. In general, the fruit quality of LD was the best. RDA analysis showed that the dominant microbe in C. migao fruits were Saitozyma, Mortierella and Arthrobacter, and that α-Terpineol, sabinene, soluble polysaccharide and crude polysaccharide could promote their accumulation. S-UE had the greatest effect on the composition of rhizosphere microbial community, followed by available P (AP) and S-CAT.

Conclusions The diversity of rhizosphere microbial community varied among different fruiting stages significantly. Ascomycota as an unidentified genus, Saitozyma, Mortierella, and Arthrobacter significantly promoted the accumulation of C. migao fruit chemical components in different fruit periods. In Luodian, C. migao fruit was mostly affected by Ascomycota (an unidentified genus), while the C. migao fruit in BP and XL were most affected by Mortierella. The rhizosphere fungi Agaricus, Fusarium and Phialophora had no obvious effect on the accumulation of terpineol and sabinene in C. migao fruit. Soil urease activity, available P content and CAT activity were the top three items that affected the variation of microbial community.