Abstract: In order to investigate the distribution of microorganisms in the roots of terrestrial orchids under different growth conditions, the differences of microbial communities in the roots under different growth conditions were analyzed by metagenomic sequencing technology, and the potential functions of these microorganisms were predicted. The results showed that the abundance and diversity of microorganisms in the roots of wild orchids were higher than that of those ochids in the cultivated condition. The main groups of microorganisms in the roots of orchids in the wild condition were Proteobacteria, Actinobacteria, and Ascomycota, while those in the cultivated condition were Proteobacteria, Basidiomycota and Viruses noname. In addition, there were significant differences in the main dominant taxa of orchid mycorrhiza fungi （OMF）in the wild and in the cultivated condition. The relative abundance of arbuscular mycorrhizal fungi （AMF） was significantly higher in the cultivation than in the wild. By predicting the metabolic functions of microorganisms in the roots under two growth conditions, it was found that functional genes for carbohydrate metabolism, amino acid metabolism, energy metabolism and metabolism of cofactors and vitamins were more abundant in the wild condition. The results of this study provided a theoretical basis for the conservation, artificial mycorrhizalization seedling cultivation, and pest control of terrestrial orchids.

Key words: terrestrial orchids, root endospheres, macrogenome, wild orchids, cultivation orchids