Dynamic Shifts in the Root Microbiota of Cultivated Paphiopedilum armeniacum during Different Stages of Growth.

Paphiopedilum armeniacum S. C. Chen et F. Y. Liu is an endangered lady's slipper orchid species with high horticultural value. As observed for other orchids, mycorrhizal fungi and endophytic bacteria play important roles in the growth and development of P. armeniacum. In the present study, the community structure dynamics across three growth and development stages of cultivated P. armeniacum were investigated. The potential interactions between Tulasnellaceae fungi and core bacterial genera on one hand and the stability of the presumed mycorrhizal fungi communities on the other were analyzed in three growth stages of P. armeniacum to enhance our understanding of endophytic microbial community structure dynamics in the roots at different development stages. Based on sequencing, 3 and 16 phyla and 59 and 269 genera were identified in the fungal and bacterial communities, respectively. The predominant fungi and bacteria were Basidiomycota (62.90%) and Proteobacteria (43.98%), which exhibited changes in abundance and diversity depending on the growth stage of P. armeniacum. Assessment of the entire microbial communities from different growth stages showed that the seedling stage had the highest richness and diversity. The microbial communities recruited by P. armeniacum at the seedling stage were different from those recruited at the vegetative and reproductive growth stages, and the microbial communities recruited in the latter two stages overlapped. Tulasnellaceae were the only dominant fungal symbionts during P. armeniacum growth. Brevibacillus, Mycobacterium, and Sphingomonas, the three core genera, showed significant interactions with the main OTUs of Tulasnellaceae. Putative mycorrhizal fungi in P. armeniacum were relatively stable across different growth environments, and the core mycorrhizal fungi were uncultured Tulasnellaceae (OTU1). This could facilitate the ex situ conservation and commercial development of the endangered orchid. [ABSTRACT FROM AUTHOR]