杨树抵御溃疡病菌侵染中类黄酮合成的遗传机制研究

Flavonoids play important roles in the resistance of plants to disease. It is necessary to identify flavonoids biosynthesis genes and elucidate genetic mechanism of defense response of trees to the infection of pathogen, which is significant for the molecular mechanism of disease resistance and breeding for tree disease resistance. In our previous research, the transcriptome analysis and metabolome detetion using poplar bark infected or not with Lonsdalea quercina have been carried out in our laboratory. Fifteen flavonoids biosynthesis genes have been detected with differential expression in response to the infection of Lonsdalea quercina. Based on these researches, the expressions of these genes are further analyzed to identify the differential expression among different inoculation stages, different inoculation spots, poplar varieties with different resistance to Lonsdalea quercina.The association between the differential expression of flavonoids biosynthesis genes and the different resistance of poplar is further established. For the key flavonoids biosynthesis genes, the specific promoters induced by the pathogen are further analyzed. Four to six expression vectors are constructed and the locolization of promoters in different plant tissues and the core elements in promoters are identified to reveal the regulaory mechanism of flavonoids biosynthesis genes in response to the infection. To further identify genes with defense function, two to three amiRNA vevetors of flavonoids biosynthesis genes are constructed and the transformation are done. The differential expression of flavonoids biosynthesis genes and the metabolic content of flavonoids are detcted in the postive transgenic poplars. This research will provide new insights for the molecular mechanism of trees resistance to pathogen and new candidate genes to breeding for tree disease resistance.

类黄酮在植物抗病中起着重要作用。在杨树抵御溃疡病菌侵染中，开展类黄酮合成的遗传机制研究，对于阐明林木抗病分子机理并加速林木抗性育种具重要理论意义和应用价值。本申请在前期已开展的杨树转录组测定和代谢组分析的基础上，对杨树中响应溃疡病菌侵染的15个类黄酮合成途径基因，解析其在感病不同时期、不同部位和不同抗性品种中的差异表达，建立类黄酮合成途径基因与不同抗性的关联；对类黄酮合成途径中的关键基因，鉴定受病菌诱导的特异性启动子，构建4-6个启动子的表达载体，分析其在杨树中的组织定位，精确鉴定启动子的核心元件，以揭示林木抗病中类黄酮合成的遗传机制；构建2-3个类黄酮合成途径基因的amiRNA载体，在杨树中进行转化，分析转基因植株类黄酮合成途径基因的表达变化和其代谢变化，对转基因植株进行抗性鉴定。通过上述研究，为林木抗病分子机理的研究提供新思考，为林木抗病分子育种提供重要基因资源。

类黄酮在植物抗病中起着重要作用。在杨树抵御溃疡病菌侵染中，开展类黄酮合成的遗传机制研究，对于阐明林木抗病分子机理并加速林木抗性育种具重要理论意义和应用价值。本研究以杨树受溃疡病菌侵染后的杨树为材料，鉴定了类黄酮合成途径相关基因、酶、激素和次生代谢物在杨树受溃疡病菌侵染的不同时间段、不同抗性品种间的变化特征，儿茶素在杨树受病菌侵染后含量显著上升，且在抗性品种中收到最显著诱导。代谢途径分析还发现代谢物涉及次生代谢途径、呼吸作用相关代谢途径和信号转导途径等。杨树类黄酮合成途径中DFR基因和LAR基因在杨树抗病中起到重要作用，不同品种中，DFR和LAR的表达量均受到病原的调控。鉴定了杨树中DFR基因和LAR基因对儿茶素的合成影响，通过构建反义表达载体转化84K杨、正义表达载体转化烟草，确定外源DFR和LAR在转基因植株中的表达所引起的生理变化，有助于阐明DFR和LAR控制儿茶素合成的分子机制，为利用抗病基因提高树木的抗病性提供参考。研究结果还对杨树溃疡病抗病品种的选择和利用，理解不同抗性品种抗病性差异的原因提供了重要参考。