硅介导番茄青枯病抗性的根际微生态调控机理

Bacterial wilt caused by Ralstonia solanacearum is one of the most destructive diseases in tomato,traditional controlling measures such as resistant varieties, pesticide application and rotation exist disadvantage. Silicon is the second most abundant mineral element in earth. As an environmentally friendly fertilizer, silicon can significantly increase plant resistance against pathogen including R.solanacearum, but the mechanism is not completely clear. Previous studies on silicon-mediated plant resistance mostly focus on aboveground, no reports were found on the relationship between silicon-mediating resistance and rhizospheric soil microecological effects. Under R.solanacearum inoculation and Si treatment, different resistant varieties of tomato are chosen as experimental materials to study: Silicon uptake, changes of soil chemical properties in rhizosphere and its relation with pathogen resistance were determined. Soil microorganism community structure and genetic diversity of rhizoshere soil induced by silicon were analyzed by using PCR-DGGE method.IC, GC-MS techniques were used to investigate the induced effects of root exudates.Differential expression of proteome of rhizosphere soil were also investigated.These results will deeply reveal rhizosphere effects and mechanism mediated by silicon under pathogen inoculation，and the results will provide theoretical basis and practical guidance for effectively controlling R. solanacearum.

青枯病是一种由青枯菌(Ralstonia solanacearum comb. nov.) 引起的毁灭性土传病害，传统的防治方法如采用抗性品种、农药防治和轮作措施均存在一定局限。研究表明硅能显著增强植物对病害（包括青枯病）的抗性，但其机理仍不完全清楚，且以往研究大多集中在地上部的抗性机理，而从调控根际土壤健康的角度研究很少。本项目通过大田与盆栽试验，在阐明硅对青枯病的防控效果及对根际土壤化学特性影响的基础上，结合 PCR-DGGE的方法，研究硅处理对根际土壤微生物群落结构、活性及多样性的影响。采用 IC、GC-MS 等技术分离和鉴定硅诱导的根系分泌物，研究其与抗病性的相关关系。通过对青枯菌侵染及硅处理的根际土壤进行差异蛋白组学分析，阐明硅提高青枯病抗性的根际土壤蛋白组学机理。研究结果有助于从根际土壤微生态的新视角阐明硅介导病害抗性的作用机理，为青枯病的有效防治提供理论依据和实践指导。

青枯病是一种由青枯菌引起的毁灭性土传病害，传统方法防治存在困难。本项目以番茄为研究对象，通过青枯菌接种和硅处理，研究根系对硅的吸收、积累和分配规律；硅处理对根际土壤微生物群落结构及活性的影响；通过对根系的差异蛋白组学和转录组学分析，阐明硅介导青枯病抗性的蛋白组学和基因表达机理。研究结果表明：.（1）硅处理能显著增加青枯病的抗性，增加土壤有效硅含量和植株根、茎、叶的硅含量，增加土壤酸性磷酸酶和脲酶的活性，显著降低土壤青枯菌数量，增加土壤中细菌和放线菌的数量，从而降低真菌/细菌比值。.（2）在接菌条件下，加硅处理能显著增加叶片抗氧化（POD, CAT，PAL）活性，上调16个蛋白，下调10个蛋白。.（3）青枯菌侵染下硅处理显著增加叶片的光合作用和根系生物量，降低感病材料的根系及根系分泌物中柠檬酸的含量，增加根系中水杨酸的含量，表明根系分泌物参与了硅调控青枯病的抗性机理。.（4）16s rDNA和ITS片段测序结果表明，Si并不影响土壤微生物多样性以及门水平上的土壤细菌和真菌微生物群落结构），但显著影响属水平上细菌群落结构，抑制Fusarium，、Pseudomonas等病原菌菌属的生长。.（5）Si能够显著影响青枯菌的基础代谢和致病过程。Si显著下调青枯菌关键致病途径-胞外多糖（EPS）合成的多个相关基因epsD，xpsR，ripAI，tek，vrg， 抑制青枯菌运动负反馈调控基因CheZ和FliN基因并促进下游鞭毛马达相关基因pilE2，pilE，fimT表达。.（6）硅处理能够延迟根部乙烯的释放，同时硅处理能够影响根部水杨酸和茉莉酸含量；推测硅介导番茄青枯菌抗性的机理可能涉及以下三方面：激活病原体相关分子模式触发免疫及效应子触发免疫；通过调节水杨酸、乙烯、茉莉酸、生长素等多激素介导的信号途径，进而改变植株抗性和耐性；硅处理缓解接种造成的负面效应（水分亏缺，盐胁迫，氧化胁迫，衰老等；.（7）大田实验结果表明，硅能增加番茄植株的茎粗、株高、干重，改善番茄品质，如蛋白质、可溶性糖、维生素含量也有一定的增加，但差异不显著。