Core Microbiome and Microbial Community Structure in Coralloid Roots of in Ex Situ Collection of Kunming Botanical Garden in China.

Endophytes are essential in plant succession and evolution, and essential for stress resistance. Coralloid root is a unique root structure found in cycads that has played a role in resisting adverse environments, yet the core taxa and microbial community of different species have not been thoroughly investigated. Using amplicon sequencing, we successfully elucidated the microbiomes present in coralloid roots of 10 species, representing all four sections of in China. We found that the endophytic bacteria in coralloid roots, i.e., , were mainly composed of _PCC-7422, _PCC-73102 and . Additionally, the Ascomycota fungi of , , , , , and were identified as the core fungi taxa. The Ascomycota fungi of Nectriaceae, Herpotrichiellaceae, Cordycipitaceae, Helotiaceae, Diaporthaceae, Didymellaceae, Clavicipitaceae and Pleosporaceae were identified as the core family taxa in coralloid roots of four sections. High abundance but low diversity of bacterial community was detected in the coralloid roots, but no significant difference among species. The fungal community exhibited much higher complexity compared to bacteria, and diversity was noted among different species or sections. These core taxa, which were a subset of the microbiome that frequently occurred in all, or most, individuals of species, represent targets for the development of conservation.