连作蕉园套作豆科绿肥抑制香蕉枯萎病发生的微生物机制研究

Banana long term monoculture destroyed the soil microbial community, thus leading to a serious soil-brone Fusarium wilt disease. In the high incidence field, intercropping was an effective measure to reduce the disease incidence. Previous work done by the applicant has been confirmed that two kinds of banana and lequminosae green manure intercropping system were high-efficiency systems in Fusarium wilt disease suppression，banana and vicia villosa roth intercropping system, banana and white clover intercropping system. However, it is still unclear about the microbial community in bulk soil of the two systems and what kind of beneficial microbes was assembled in the rhizosphere of banana, which was recruited from the bulk soil affected by intercropping. And who was the key factor in formation of this microbial community was also unknown. In this research program, MiSeq high-throughput sequencing and qPCR technique will be used to decipher the microbial community in the bulk soil and banana rhizosphere. Furthermore, who was the key factor in formation of this microbial community will be explored by the addition of vicia villosa roth and white clover root exudate and plant residue. Finally, this project will provide the theoretical guidelines for overcoming the biological obstacle of banana continuous cropping.

香蕉长期连作致使土壤微生物群落失衡，导致土传枯萎病严重发生。在高发病蕉园中，套作可以有效缓解其连作障碍。申请者前期通过田间试验验证了两种有效缓解香蕉土传枯萎病病情的套作体系，即香蕉-毛苕子和香蕉-白三叶草套作体系。但此体系中土壤微生物区系如何变化，进一步的香蕉根系从土壤中招募何种微生物形成健康的根际微生物区系尚未研究，影响其形成的关键因子尚不明确。本项目拟利用MiSeq高通量测序技术辅以实时荧光定量qPCR技术，通过田间试验结合室内试验，解析两种套作体系的蕉园土壤微生物区系特征，并通过根系分泌物和豆科绿肥残体的添加试验，探究菠萝轮作形成健康土壤微生物区系的关键因子。最终为香蕉园套作豆科绿肥防控香蕉连作障碍提供理论指导。

在高病蕉园（发病率大于 40%）中套作豆科绿肥毛苕子和白三叶草后，香蕉枯萎病的发病率显著降低。套作处理中可培养病原菌数量明显降低。在此背景下，本项目探究了香蕉园套作豆科绿肥过程中蕉园土体和香蕉根际土壤微生物群落物种多样性和功能多样性，并通过植株残体的添加试验探明影响健康香蕉根际微生物区系形成的关键因子，并获得其中有效抑菌成分。从土壤微生物群落结构和功能的角度揭示香蕉园套作豆科绿肥防控香蕉枯萎病有效性的形成机制，为防控香蕉连作生物障碍提供理论依据，最终为实现香蕉产业可持续发展提供重要的理论参考。结果表明：随着绿肥种植时间的延长，土壤微生物群落结构和多样性逐渐发生变化。套作绿肥能显著降低抽蕾期和成熟期土壤中尖孢镰刀菌的丰度，增加与防治枯萎病相关的青霉属、曲霉属、木霉属、Gp1属和假单胞菌的丰度。同时蕉园套作白三叶草可以阻断尖孢镰刀菌从发病植株土壤向健康植株土壤的传递，从而使有白三叶草相隔的健康植株，维持自身的土壤微生物群落结构不受周围发病植株的影响。套作绿肥能明显抑制病原菌在土壤中的繁殖，而促进与防枯萎病相关的青霉、曲霉、木霉和Gp1属在土壤中富集。且套作绿肥对病原菌的抑制作用和对有益微生物的激发作用，随着距绿肥植株距离的增加而减弱。.从香蕉套作毛苕子和白三叶的处理中筛选的生防微生物，通过各种途径来抵御有害病菌，并且抑制病原菌生长，从而减少其对植物生长和发育的影响。.绿肥根系分泌中的氢化肉桂酸和马来酰亚胺对病原菌具有较好抑制作用，而富马酸、L-苹果酸、维生素C、月桂酸、十五烷酸、L-异亮氨酸、10-羟基癸酸、D-葡萄糖醛酸也存在部分抑制作用。同时富马酸和苹果酸可能会对拮抗微生物的生长起到正向促进的作用，从而起到抑制尖孢镰刀菌的作用。