广西甘蔗根围深色有隔内生真菌多样性与生态功能研究

Guangxi is the sugarcane main production area in China, however, 90% sugarcane are planted in arid hillside field and hard to conserve water and fertilizer which caused tremendous production loss. Give full play to the potential of symbiotic microorganism's plant growth promotion and adverse resistance functions in nature ecology system can improve sugarcane production and conservation of sugarcane filed ecosystem. we had obtained two DSE isolates from sugarcane rhizosphere in the suburb of Nanning city which could promote sugarcane growth significantly, this suggested that DSE may play a important ecological role in sugarcane filed ecosystem. To full excavate the DSE resource from sugarcane rhizosphere, in this research, we will study the DSE species diversity in sugarcane rhizosphere, isolate the DSE fungi in rhizosphere soil of different sugarcane habitat by using egg plant as bating plant, and identify DSE species according to the morphology and the sequence analysis of the ITS ,SSU and LSU regions of rDNA, and screen for the effected isolate by study the effect of DSE fungi on the growth promotion and drought-resistant ability of sugarcane.The objective of this study is to clear understanding of the DSE species diversity and distribution in sugarcane rhizosphere and obtain the ecological functional DSE strain, this result has good promote to study of DSE ecological function in natural ecosystem, and will provide theoretic basis to use DSE biotechnology for raising sugarcane production capacity and conservation of sugarcane filed ecosystem.

广西是我国甘蔗主产区，然而蔗地90%以上为旱坡地，土壤保水保肥能力差，给生产带来巨大损失，充分挖掘自然生态系统中共生微生物的促生和抗逆潜力，可提高我国甘蔗生产能力、保护和改善蔗地生态环境。在前期研究中,我们从南宁市郊甘蔗根围分离获得2株能显著促进甘蔗生长的DSE菌株，发现DSE在蔗地生态系统中可能扮演着较为重要的生态角色。为了进一步全面发掘甘蔗根围DSE资源，本研究拟对广西主蔗区甘蔗根围的DSE物种展开系统的调查研究，采用茄科植物诱捕分离根围土壤的DSE菌株，并结合形态学和核糖体DNA的ITS 、SSU和LSU序列分析对其进行分类鉴定，通过建立"DSE-甘蔗"共生体，探讨DSE对甘蔗生长、抗旱能力的影响，目的在于明确广西甘蔗根围DSE的物种多样性与分布、筛选到对甘蔗具显著促生和提高抗旱能力的菌株，为探明DSE在自然生态系统中的作用、利用其促进甘蔗生产的节肥减耗及蔗地生态的良性循环提供依据。

深色有隔内生真菌（DSE）是一类与宿主互惠共生，具有能提高宿主抗逆性、分布广泛和可培养的尚待开发利用的微生物资源。本研究以广西主要经济作物—甘蔗的根围土壤为分离源，对广西10个甘蔗主产区进行了采样，采集了170份土样，从诱捕分离到的3166内生真菌株中，筛选获得DSE菌株117株，分离率为3.8%。结合形态学特征及ITS、SSU和LSU等基因序列分析，将菌株鉴定为子囊菌门的55个分类单元；将52株产孢菌株鉴定为19个属29个种，发现新种8个Conlarium nanningense、Conlarium sacchari、Conlarium baiseense、Tetracladium botryospora、Tetracladium vietus、Piriformospora sacchari、Ochroconis septispora、Phaeoacremonium sacchari。DSE在甘蔗根围普遍定殖，其优势属为Cladophialophora、Conlarium、Cladosporium、Helicoma、Chaetosphaeria、Ochroconis。甘蔗根围DSE具有丰富的物种多样性（S，74；H'，4.32；1 – D，0.99），地理位置显著影响DSE的分离、群落的组成、分布和多样性。筛选获得多株对宿主具促生、提高抗旱和抗病能力的优良功能菌株，菌株通过调节宿主的抗氧化酶活性、增强光合作用等生理变化提高在胁迫环境下的抗逆能力。研究结果丰富了我国DSE真菌的物种资源库，并为DSE菌株在农业生态环境保护的应用提供理论依据。