Diversity of endophytic fungi in Orah mandarin roots in Guangxi

【Objective】This paper investigated the effects of clean tillage and grassing measures on the diversity of endophytic fungi in Orah mandarin roots，to provide a scientific basis for screening and developing beneficial endophytic fungal resources with functions such as growth promotion，disease prevention and stress resistance.【Method】 Six representative Orah mandarin orchards in Wuming District，Nanning City， Guangxi（three grassing mode and three clean tillage mode）were selected to investigate their soil nutrient levels. And the ITS zones of endophytic fungi in Orah mandarin roots were determined using high-throughput sequencing technology to analyze the diversity of fungal communities in Orah mandarin root samples and their distribution patterns.【Result】 The soil of Orah mandarin orchards in Wuming District， Nanning， Guangxi was mainly acidic， being rich in available potassium and organic matter. Endophytic fungi were detected in endophytic fungi in Orah mandarin root samples，including 12 phylums，42 classes，102 orders，224 families and 416 genera of endophytic fungi，of which the main dominant taxa at the phylum level was Ascomycota，and at the genus level were Neocosmospora，Penicillium. There was no great difference in the community structure of endophytic fungi in Orah mandarin roots under natural grassing and clean tillage modes. The results of canonical correlation analysis（CCA） showed that the fungal communities in Orah mandarin root were highly significantly correlated with nitrate nitrogen， ammonium nitrogen and soil organic matter（P＜0.01），significantly correlated with pH（P＜0.05），and not significantly correlated with available phosphorus and available potassium（P＞0.05）. The structures of nutrient functional groups in the root system were similar in all the experimental orchards，with the highest relative abundance of saprophytic-nutrient endophytic fungal communities，followed by unidentified functional groups，pathological-saprophytic-symbiotic nutrient fungal communities. And the other nutrient functional groups occupied lower proportions in different orchards.【Conclusion】The dominant genera of fungi in Orah mandarin roots in Guangxi are dominated by the genera Neocosmospora， Penicillium. The endophytic fungal community composition in the roots of Orah mandarin at this regional scale is not significantly related to grassing management，but is regulated by some soil environmental factors.