Abstract: The diversity and community composition of endophytic fungi in Oxytropis chrysantha at different altitude gradients were analyzed to provide a new way to control the yield of swainnonine. The ITS sequences of endophytic fungi in Oxytropis chrysantha at different altitude gradients (2 512,3 005,3 490,3 977 and 4 493 m) on the Qinghai-Tibetan Plateau were determined by high-throughput sequencing technique. The variation of fungal diversity and community composition with altitude was observed. The redundancy analysis (RDA) was conducted using CANOCO 5.0 software between relationships of dominant fungal communities,plant nutrition and soil environmental factors. The results showed that there were significant differences in plant nutrition and soil physical and chemical properties at different altitude gradients. 3615854 ITS sequences were obtained from Oxytropis chrysantha samples of five altitude gradients,and 750 OTUs were classified based on 97% sequence similarity. The richness index of fungal community (Chao1) was the highest at 4 493 m (254.10),while the Shannon index was the highest at 3 005 m(3.05). Ascomycota and Basidiomycota are the dominant endophytic fungi of Oxytropis chrysantha in the Qinghai-Tibetan Plateau. RDA analysis showed that dominant fungal groups were significantly correlated with altitude,crude ash and soil organic carbon (P<0.01),and with nitrogen,phosphorus and nitrogen-free extracts (P<0.05). The results showed that the diversity of endophytic fungi in Oxytropis chrysantha was affected by altitude,plant nutrition and soil nutrient content.

Key words: Oxytropis ochrocephala, Altitude gradients, High-throughput sequencing, Endophytic fungus, Diversity

摘要： 为了分析不同海拔梯度黄花棘豆（Oxytropis ochrocephala）内生真菌的多样性及群落结构，进而为调控其主要成分-苦马豆素产量提供新的途径。本试验采用高通量测序技术测定青藏高原不同海拔梯度（2 512，3 005，3 490，3 977和4 493 m）黄花棘豆中内生真菌的ITS序列，观测真菌多样性和群落组成随海拔升高的变化情况，并运用CANOCO 5.0软件对真菌优势群落与植物营养和土壤环境因子间的关系进行冗余分析（Redundancy analysis，RDA）。结果表明：不同海拔梯度植物营养成分及土壤理化性质间均差异显著；从5个海拔梯度的黄花棘豆的样本中获得3615854条ITS序列，在97%序列相似性基础上可划分为750个分类单位（Operational Taxonomic Units，OTUs）。真菌群落的丰富度（Chao1）指数以海拔4 493 m最高，为254.10，而多样性（Shannon）指数以海拔3 005 m最高，为3.05。子囊菌门（Ascomycota）和担子菌门（Basidiomycota）是青藏高原黄花棘豆内生真菌的优势类群。RDA分析结果显示，真菌优势类群与海拔、粗灰分和土壤有机碳呈极显著相关（P<0.01），与氮、磷和无氮浸出物呈显著相关（P<0.05）。海拔、植物营养及土壤养分含量均会影响黄花棘豆内生真菌多样性。

关键词: 黄花棘豆, 海拔梯度, 高通量测序, 内生真菌, 多样性