分蘖洋葱套作抑制番茄黄萎病的根际微生物学机理

Soil sickness has become an important constraint of the sustainable development of facility vegetable industry, soil-borne disease is one of the main causes of soil sickness. Our previous study found that intercropping Potato onion (Allium cepa var. agrogatum Don.) can inhibit tomato (Solanum lycopersicum) Verticillium wilt. However, the mechanism involved is still unclear. This study will further (1) clarify the abundance, composition and function of tomato rhizosphere microbial communities with quantitative PCR, 16S rDNA amplicon and metagenomic sequencing, and evaluate the relationship of changes in tomato rhizosphere microbial communities with the resistance to Verticillium wilt with plant-soil microorganism feedback experiments; (2) isolate the PGPRs that recruited in tomato rhizosphere in the intercropping system and elucidate their effects on the resistance of tomato to Verticillium wilt and induction of ISR in tomato; (3) elucidate the effects of intercropping Potato onion on tomato root metabolism with UPLC-Q-TOF/MS and HPLC, reveal the changes in tomato root exudates induced by Potato onion; (4) study the effects of intercropping Potato onion, tomato root exudates on the recruitment of PGPRs by tomato and the antagonistic activity of PGPRs using split-root experiment. This project is expected to reveal the rhizosphere microbial mechanism of intercropping Potato onion inhibit tomato Verticillium wilt. Overall, this study could provide theoretical foundation and technical support for the application of Potato onion/tomato intercropping system, and relieving soil sickness through increasing plant diversity.

连作障碍是制约设施蔬菜产业可持续发展的重要瓶颈，土传病害是连作障碍发生的重要因子。申请者发现分蘖洋葱套作可以减轻番茄黄萎病病害，但机理不明。本项目拟在已有研究的基础上，(1)通过定量PCR、16S rDNA扩增子及宏基因组测序等，阐明分蘖洋葱套作对番茄根际微生物菌群丰度、结构、功能的影响，通过植物-土壤微生物反馈实验揭示番茄根际微生物变化与黄萎病病害发生间的关系；(2)分离鉴定出套作番茄根际加强招募的PGPR，明确其对番茄黄萎病抗病力及ISR的影响；(3)利用UPLC-Q-TOF/MS、HPLC等技术，揭示分蘖洋葱套作对番茄根系代谢的影响，确定番茄根系分泌物组分的变化；(4)采用分根实验等，探明套作及番茄根系分泌物对PGPR根际定殖及拮抗力的影响。通过该研究阐明分蘖洋葱套作抑制番茄黄萎病的根际微生物学机理，为分蘖洋葱套作番茄栽培模式的应用以及通过植物多样性缓解连作障碍提供理论与实践基础。

连作障碍是目前制约设施蔬菜产业可持续发展的重要瓶颈，土传病害是连作障碍发生的重要因子之一。我们发现分蘖洋葱套作可以减轻番茄黄萎病病害，本研究进一步解析了分蘖洋葱套作抑制番茄黄萎病的根际微生物学机理。16S rDNA扩增子及宏基因组测序发现，套作分蘖洋葱改变了番茄根际微生物群落组成及功能，尤其提高了芽孢杆菌的丰度。植物-土壤微生物反馈实验实验证明了套作分蘖洋葱通过改变番茄根际微生物群落而抑制番茄黄萎病。通过平板培养法分离鉴定了番茄根际富集芽孢杆菌，并筛选出了对黄萎病菌具有较好抑制能力、且能诱导番茄产生系统诱导抗性的菌株Bacillus sp. B56。分根实验发现，套作分蘖洋葱促进了番茄对芽孢杆菌B56招募。进一步的体外实验表明，套作处理的番茄根系分泌物比单作处理番茄根系分泌物对芽孢杆菌B56的趋化性和生物膜形成具有更强的促进能力。HPLC等分析发现，套作分蘖洋葱改变了番茄根系代谢，尤其促进了有机酸等的分泌。番茄根系分泌物中所增加的有机酸（如苹果酸、柠檬酸）等对芽孢杆菌B56的趋化性和生物膜形成也具有促进作用。综上，套作分蘖洋葱通过改变番茄根际微生物，尤其是促进番茄对有益微生物的招募从而抑制了番茄黄萎病。