云南元江干热河谷五种优势植物的内生真菌多样性

从蔓草虫豆（Atylosia scarabaeoides）、余甘子（Phyllanthus emblica）和黄花稔（Sida acuta）等5种云南元江干热河谷植物的525个组织块中，共分离得到内生真菌371株，内生真菌的分离频率在0.61～0.92之间，且所有植物叶内生真菌的分离频率都明显高于茎（P<0.05）。经形态学鉴定，内生真菌分属于拟茎点霉属（Phomopsis sp.）、离蠕孢属（Bipolaris sp.）和交链孢属（Alternaria sp.）等32个分类单元。拟茎点霉属为干热河谷植物优势内生真菌属，从所有被调查植物的茎叶中都分离得到该属真菌，且相对分离频率高达12.90%～50.54%。内生真菌群落组成的多样性和相似性分析结果表明，云南元江干热河谷植物内生真菌多样性偏低、宿主专一性较小。

Endophytic fungal diversity of five dominant plant species in the dry-hot valley of Yuanjiang, Yunnan Province, China

Fungi causing asymptomatic infections in living plant tissues have been called endophytic fungal. They comprise a diverse group of fungi and may protect their host plants against the insect pests and phytopathogens, increase hosts fitness in extreme environments. In order to document the ecological relationship between endophytic fungal and their host plants which grown in hot and dry stressed environments, the endophytic fungal diversity, the dominant fungi and their host specificity of 5 dominant plant species (Atylosia scarabaeoides, Azadirachta indica, Phyllanthus emblica, Broussonetia papyrifera and Sida acuta) which grown in the dry-hot valley of Yuanjiang Yunnan Province, southwest China were studied in present research works. A total of 371 endophytic fungal were isolated from 525 tissue segments of the 5 plant species. The isolation rate was 0.71. The highest isolation rate appeared in S. acuta, it was 0.92, while the lowest isolation rate appeared in A.indica, it was only 0.61. It was found that the isolation rate of leaves endophytic fungal was significantly higher than that of stems (P<0.05) in the 5 plant species. Based on their morphology and the mechanism of spore production, the sporulating isolates were identified to genus level. Non-sporulating isolates were identified as mycelia sterile and sorted into different groups based on the colony surface texture, hyphal pigmentation and growth rates after two months sporulation. The isolated fungi were finally identified to 32 taxa including Phomopsis, Colletotrichum and Alternaria etc. The endophytic fungal richness of the 5 plant species was different. The highest endophytic fungal richness appeared in A. scarabaeoides, from which 20 endophytic fungal taxa were obtained, whereas the fungi from A. indica were just 11 taxa and showed the lowest richness. Each plant species harboured 1 to 2 dominant fungi. The dominant fungi of A. scarabaeoides were Bipolaris sp. and Phomopsis sp., the relative frequency was 38.81% and 14.93% respectively. Phomopsis sp. and an ascomycete species were the dominant fungi of A. indica and P. emblica, the relative frequency of Phomopsis sp. was 12.90% and 40.24%, the relative frequency of the ascomycete was 33.87% and 17.07% respectively. The dominant fungi of B. papyrifera and S. acuta was Phomopsis sp., the relative frequency was 49.25% and 50.54% respectively. The results showed that Phomopsis was the dominant fungi of the dominant plant species in the dry-hot valley of Yuanjiang, Yunnan Province, China, its relative frequency got a range of 12.90% to 50.54%. The diversity index of endophytic fungal from A. scarabaeoides, A. indica, P. emblica, B. papyrifera and S. acuta were 0.77, 0.62, 0.65, 0.82 and 0.90 respectively, and it was little lower than that of some previous reports from tropical plants. The diversity index of endophytic fungal from leaves was 0.33 to 0.64, it was higher than that from stems (0.28-0.39). The similarity index of endophytic fungal from the 5 plant species ranged from 0.483 to 0.757, and the highest similarity index appeared in A. scarabaeoides and S. acuta (0.757), and the lowest similarity index appeared in A. indica and P. emblica, it was only 0.483. These results suggested that the host specificity of endophytic fungal from the dominant plant species in the dry-hot valley of Yuanjiang Yunnan Province, China was low.