嫁接番茄根系分泌物提高番茄对青枯病抗性的作用及其机理研究

To fill up the research blank about the effect and mechanism of the root exudates of rootstock-grafted tomato plants on the improvement of the resistance to the bacterial wilt. In this study, we will adopt two rootstocks respective named ‘Fan zhen No.1’ and ‘Qie Zhen NO.21’ with high resistance to the bacterial wilt as the rootstocks, one tomato cultivar ‘Fen Beibei’ which is high sensitive to the bacterial wilt as the scion. The rootstock-grafted plants and self-grafted tomato plants were inoculated with Ralastonia solanacearum, respectively. The root exudates of rootstock-grafted plants and self-grafted plants before the inoculation and different times after inoculating will be collected and then concentrated. The constituents and their relative contents of root exudates will be determinated by gas chromatography-mass spectrometry (GC-MS) and the different constituents and/or unique constituents of the root exudates between the rootstock-grafted plants and self-grafted plants will be identified. The relationships between these different and/or unique constituents and three factors including the disease resistances to the bacterial wilt, the quantity of Ralastonia solanacearumin different organs and the changes of the population of their rhizosphere microbial in rootstock-grafted plants and self-grafted plants will be analyzed. The different component of root exudates from rootstock-grafted plants will be obtained by the methods of extraction using different organic solvent and then be diluted into different concentrations. The different concentrations of different component will be applied to the plants of ‘Fen Beibei’ with the inoculating Ralastonia solanacearum to estimate the effects of root exudates on the effects on the inhibition to Ralastonia solanacearum and the resistance to the bacterial wilt in own-root tomato plants. Then, the component which is showed highest inhibition on the resistance to the bacterial wilt will be determinate by GC-MS. This study will clarify the mechanism of root exudate on the improvement of the resistance to the bacterial wilt in the tomato plants, and it will offer key information for the breeding of rootstocks with high resistance to the bacterial wilt and the prevention for the bacterial wilt in tomato plants in the future.

针对嫁接番茄的根系分泌物对提高番茄抗青枯病的作用及机理研究的空白，本研究采用高抗青枯病的番茄砧木‘番砧1号’、茄子砧木‘茄砧21号’分别与高感青枯病的番茄品种‘粉贝贝’进行嫁接，对两种砧木嫁接植株和接穗自根嫁接植株进行接种番茄青枯菌处理，在接种前、接种后发病初期和高峰期分别收集根系分泌物并制备浓缩液，使用气相色谱-质谱联用（GC-MS）测定根系分泌物的物质成分和相对含量，明确不同嫁接植株根系分泌物的差异或特异成分，并分析其与植株的抗病性表现、植株体内的青枯菌及根际微生物主要生理种群数量变化的相关性。结合对比不同有机溶剂萃取得到的根系分泌物不同组分及不同浓度对青枯菌的抑制作用和防病效果，明确最优抑菌活性组分的物质成分，阐明抗病砧木嫁接植株的根系分泌物对提高番茄抗青枯病的作用机理。研究结果为利用根系分泌物中的抑菌活性物质成分信息指导抗青枯病砧木育种和有效防治青枯病提供理论参考。

嫁接栽培是防治番茄重要土传病害青枯病的最有效技术手段，根系分泌物是植物根系和土壤之间的重要媒介，在调控根际微生物和植株抗病中发挥着重要作用。嫁接番茄的根系分泌物如何调控植株抗病、哪些组分起主要作用，是本研究解决的科学问题。研究结果揭示了嫁接砧木的根系分泌物提高番茄抗青枯病的作用机理，为番茄青枯病的防治开辟了新途径。.1.明确了嫁接番茄抗病表型与根际病原菌、微生物数量的相关性。通过平板分离培养和高通量测序，发现抗病砧木嫁接可有效阻止青枯菌侵染嫁接植株根系和茎部，抑制增殖，从而降低发病率和减轻发病程度。病情指数、发病率、青枯菌数量与根际微生物、细菌、放线菌数量正相关，与真菌数量负相关。抗病砧木嫁接显著提高根际细菌和放线菌的数量，降低真菌数量和丰度，增加有益微生物丰度，从而提高嫁接植株的抗病性。.2.明确了不同砧木嫁接植株的根系分泌物组分及相对含量。通过GC-MS测定分析，明确了根系分泌物中邻苯二甲酸二甲酯、邻苯二甲酸二丁酯、邻苯二甲酸二异辛酯、2，4-二叔丁基苯酚、2，6二叔丁基对甲苯酚等5种物质与抗青枯病有关。.3.证明了抗病砧木嫁接植株的根系分泌物具有提高番茄抗青枯病的作用。灌根试验结果表明，抗病砧木嫁接植株的根系分泌物对青枯病具有显著的抑菌作用和防病效果，最高抑菌率达18.63%，发病率降低10.00%，病情指数降低12.49%。.4.筛选出模拟根系分泌物防治青枯病的最优组分和浓度。利用化学物质模拟根系分泌物活性物质进行化感验证，抑菌和防病效果最优的是：1.0mL•L-1的2，4-二叔丁基苯酚的抑菌率达51.32%，同浓度邻苯二甲酸二丁酯的发病率降低47.78%；1.0mmol•L-1同浓度的邻苯二甲酸二甲酯和2，6二叔丁基对甲苯酚混合物的发病率降低至46.7%。