低发土传枯萎病蕉园根际微生物区系特征解析及其调控机制

Analysis of rhizosphere microflora in banana plantation with low fusarium wilt disease incidence could provide the theoretical basis for preventing banana continuous cropping obstacle. Banana orchards that still maintain a low banana Fusarium wilt disease incidence after consecutive years of banana planting have been found in the Hainan Island, China. However, the characteristics of the rhizosphere microflora and its formation mechanism from bulk soil in these low-disease banana plantations are still unknown. Previous studies have demonstrated that combined application of fumigation using ammonium bicarbonate mixed with lime and bio-organic fertilizer could effectively suppress the disease. However, what kind of microbial community created after fumigation and bio-organic fertilizer application and what mechanism involved in rhizosphere microflora reconstruction from bulk soil need deep investigation. In addition, the relationship between rhizosphere microflora from investigation and regulation also need deep investigation. In this project, MiSeq sequencing technique will be used to analyze the specific microbial community and structure. Real-Time PCR technique will be used to detect the number of microbes. Then the characteristics of the rhizosphere microflora and its formation mechanism from bulk soil in low-disease banana plantations from investigation and regulation will be studied. This project will find out the mechanism involved in rhizosphere microflora reconstruction from bulk soil and provide an important theoretical basis for preventing the continuous cropping obstacle of banana planting.

低发土传枯萎病蕉园根际微生物区系特征解析是防控香蕉连作生物障碍理论基础。申请人前期在海南省广泛调查获得长期连作低发枯萎病蕉园，但根际微生物区系特征及其如何由土体微生物区系孵育形成亟待研究。前期研究同时证实石灰+碳铵熏蒸联用生物有机肥技术能够有效防控连作香蕉枯萎病的发生，进而形成低病蕉园，但熏蒸联合生物有机肥施用造成的土壤微生物区系变化、调控后的根际微生物区系与调查所得低病蕉园抑病根际微生物区系之间的关联性还有待深入研究。本项目拟利用MiSeq测序技术分析土壤微生物具体类群，辅以Real-Time PCR技术测定微生物数量，分析阐明大尺度调查所得低发病蕉园根际微生物区系特征及其由土体微生物区系孵育形成机制，结合石灰+碳铵熏蒸联用生物有机肥调控所成土体及根际微生物区系特征，探明调控土体土壤微生物区系形成抑病根际微生物区系的机制，最终为防控香蕉连作生物障碍提供理论依据。

解析低发土传枯萎病蕉园的根际微生物区系特征是防控香蕉连作生物障碍的理论基础。本项目通过比较海南6处抑制香蕉土传枯萎病的抑病型蕉园及周边导病型蕉园的土壤微生物区系特征，解析了香蕉抑病型土壤的微生物区系特征及其驱动因子，其中土壤pH和总碳为驱动抑病型微生物区系形成的关键因子。通过病原菌入侵灭菌和未灭菌的导病及抑病型土壤，研究了导病及抑病型土壤响应病原菌入侵的微生物特征。病原菌入侵显著影响了抑病和导病型土壤中细菌的Alpha和Beta多样性，抑病型土壤中的细菌群落能更快的应对病原菌入侵，Chryseolinea、Ohtaekwangia和Terrimonas是抑病型土壤中抑制尖孢镰刀菌入侵的潜在关键微生物类群。抑病型和导病型土壤构建形成了截然不同的根际微生物群落结构，病原菌入侵显著改变了导病型土壤构建的根际细菌和真菌群落结构，而仅显著改变了抑病型土壤构建根际中的真菌群落结构，抑病型土壤构建的根际中蓝状菌属微生物为特有响应微生物，而Simplicillum、非香蕉枯萎病专化型镰刀菌属和毛壳菌科微生物为有效抵御病原菌入侵的潜在关键微生物。探明了连续施用生物有机肥增强土壤抑病能力的土壤微生物生态学机理，生物有机肥中的有机载体能够有效促进功能微生物芽孢杆菌在土壤中的定殖，其能够有效激发土壤中有益土著菌的增殖，尤其是假单胞菌属的数量，芽孢杆菌和假单胞菌联合激发土壤抗病能力。建立了土壤熏蒸联合生物有机肥施用调控土壤微生物区系的模式，并探明了健康土体和根际微生物区系的调控机制，熏蒸及施用生物有机肥通过改良土壤基本理化性状（如pH及有机质）从而形成抑病型土壤微生物。此外，熏蒸后施用生物有机肥能通过1）改变土壤和根际细菌群落组成，2）增加细菌及真菌系统发育多样性指数，3）降低土壤中尖孢镰刀菌的数量，及4）激发土壤中诸如芽孢杆菌属、假单胞菌属、诺卡氏菌属及被孢霉属等土著有益菌群丰度的上调进而调控形成具有抑病能力的土壤和根际。