Diversity And Cold Adaptation Of Endophytic Fungi From Five Dominant Plant Species Collected From The Baima Snow Mountain, Southwest China

Endophytic fungi represent an important and quantifiable component of fungal biodiversity. The study of endophytic fungal diversity provides abundant information to understand the fungal diversity. Alpine forests (altitudes above3,000m) are a specific terrestrial cold environment and are subjected to large temperature fluctuations, a high number of days of frost and ice, regular freeze-thaw events and a high amount of precipitation. To our knowledge, no reports on the endophytic fungal diversity and their ecological roles in this specific environment are available. In the present study, the diversity and the cold adaptation of endophytic fungi from five dominant plant species in the alpine forests of the Baima Snow Mountain Nature Reserve, Yunnan Province, Southwest China were investigated. The results would provide a clear insight into the endophytic fungal diversity in alpine forests in cold environment and also contribute to our understanding of the ecological roles and the evolution of the endophytic fungi in this environment.(1) The endophytic fungal diversity of5dominant plant species(Quercus spinosa, Quercus pannosa, Rhododendron sp.1, Rhododendron sp.2, and Rhododendron sp.3) collected from the Baima Snow Mountain, Yunnan Province, Southwest China, were investigated. A total of604culturable endophytic fungi were isolated from800stems and leaf segments. The colonization rate of endophytic fungi in the five plant species ranged from54%to91%, and the colonization rate of endophytic fungi in the stems was significantly higher (87%) than that in the leaves (67%)(X (?)2=45.172, P<0.001, chi-squared test). These results suggested that endophytic fungi colonized in the plants widely.(2) Based on the morphological characteristics and the ITS sequence analysis, the isolates were identified to43taxa, including Cephalosporium, Sirococcus, Penicillium, Cladosporium and so on, of which Cephalosporium, Sirococcus, Penicillium and Aspergillus were the dominant genera, and the relative frequencies of them were14.06%,12.58%,9.44%and7.95%, respectively. Cephalosporium, Penicillium and Aspergillus were the most common endophytes, while Sirococcus has never been reported as an endophyte to date.(3) The Sorenson’s coefficient similarity indices of the endophytic fungi from the five plant species ranged from0.522to0.694, and different plants harbored different fungal taxa. Some fungal taxa were found only in certain plant genera or plant species, which showed a certain level of host and/or tissue specificity. However, some of the fungal taxa co-existed in all five of the plant species. The results suggest that some of the endophytic fungi are host-generalists.(4) The Shannon-Weiner diversity indices of the endophytic fungi from the five plant leaves and stems were2.41,2.01,1.85,1.85,2.07, and1.25,2.43,2.15,2.69,2.41, respectively. These results suggested that the endophytes from the Baima Snow Mountain have high diversity.(5) In the present study, the cold adaptation of dominant endophytic fungal genera strains was investigated, too. The Growth temperature tests indicated that75%of the isolates from the Baima Snow Mountain were psychrotrophs and14%were the transitional type between psychrotrophs and mesophiles, whereas all of the isolates from the Yuanjiang Dry-hot Valley were mesophiles. These results suggested that the endophytes from the Baima Snow Mountain possess a remarkable ability to adapt to cold environments.