Microbiota Diversity of Festuca Sinensis Seeds in Different Location of Qinghai-Tibet Plateau

Background: The Qinghai-Tibet Plateau is characterized by strong ultraviolet rays, extended sunshine durations, high altitudes, substantial temperature differences between day and night, dry air, and poor soil water and fertilizer preservation ability[54]. Although the environment and climatic conditions of the Qinghai-Tibet Plateau and growth conditions of plants are well known, relatively few studies have been conducted on the effects of environmental factors on seed microbiota diversity on the Qinghai-Tibet Plateau. Festuca sinensis is a cool-season perennial grass species suitable for growth on the Qinghai-Tibet Plateau. Therefore, investigating the Festuca sinensis seed microflora diversity could play an important role in establishing plant species diversity on the Qinghai-Tibet Plateau. Results: Festuca sinensis seeds were collected from 14 locations on the Qinghai-Tibet Plateau, and their endophyte status and seed microflora were analyzed to determine the effects of endophytes and host growth environment on the microflora of F. sinensis seeds. The results showed that the endophyte infection rate of these germplasms ranged from 0% to 80%. Endophyte infection rates were significantly negatively correlated with elevation(P<0.05)and significantly positively correlated with monthly mean temperature (MMT)(P<0.05)and growing monthly mean temperature (GMMT)(P<0.01). Microflora analysis using high-throughput sequencing showed that Proteobacteria, Cyanobacteria, and Bacteroidetes were the most abundant bacteria at the phylum level, and Ascomycota and Basidiomycota were the most abundant fungi at the phylum level in seeds. Regarding the relative abundance of each phylum in different seed lots, significant differences occurred among the 14 ecotypes. Bacterial and fungal diversity indices, including Chao1, Shannon, Simpson, and Adaptive Communication Environment (ACE), showed significant differences among these 14 ecotypes, although they were not consistent among the indices. These diversity indices were correlated with the host growth environment. For example, the Chao richness and ACE indices of bacteria were significantly negatively correlated with monthly mean precipitation, annual mean precipitation, and growing monthly mean precipitation(P<0.05). The Chao richness index of fungi was significantly negatively correlated with MMT, annual mean temperature (AMT), and GMMT (P<0.05). The ACE index of fungi was significantly negatively correlated with MMT, AMT, and GMT(P<0.01). The relative abundance (ACE index) of fungi was significantly positively correlated with elevation. The Chao richness index of fungi was significantly negatively correlated with MMT, AMT, and GMMT.Conclusions: These results suggest that average precipitation had significant effects on the abundance of bacteria, whereas the endophyte infection rate, elevation, and average temperature significantly affected the abundance of fungi. Temperature and elevation had significant effects on the endophyte infection rate.