Defence reactions during Cuscuta reflexa infection

根和无叶植物寄生物反曲菟丝子通过菌丝将水和营养从宿主转移到寄生物而穿透宿主植物。菟丝子侵染几乎所有的草本植物，因此是世界各地温暖气候下的重要害虫。只有极少数的植物物种，如年轻的西红柿，能够击退C。由过敏反应引起的反射。我们可以表明，作为对菟丝子接触的响应，番茄改变了局部Ca 2+浓度并表达了编码细胞壁修饰蛋白的基因。该项目的目的是了解寄生虫-宿主相互作用过程中的分子事件，并制定新的防治菟丝子感染的策略。在前期工作中，建立了番茄的消减cDNA文库，并差异筛选了番茄中由于C.反射攻击防御反应现在将通过RNAi和病毒诱导的基因沉默技术研究这些序列来分析，以识别防御基因。对于基因表达研究，将进行启动子与GUS或荧光素酶的融合以及通过相应测定的分析。用番茄cDNA转化烟草亲和寄主，表明这些基因与番茄对烟草赤星病的抗性有关。反射攻击

The root and leafless plant parasite Cuscuta reflexa penetrates a host plant by hyphae that transfer water and nutrition from the host to the parasite. Cuscuta infects virtually all herbaceous plants and thus is an important pest plant in warm climates all over the world. Only very few plant species, like e.g. young tomatoes, are able to repel C. reflexa by a hypersensitive reaction. We could show that, as a response to Cuscuta-contact, tomato changed local Ca2+-concentrations and expressed genes coding for cell wall modification proteins. The aim of the proposed project is to understand molecular events during this parasite-host interaction and to develop new strategies against Cuscuta infection. In preliminary work a subtracted cDNA library of tomato was built up and differentially screened for genes which are upregulated in tomato due to C. reflexa attack. Defence reactions will be now analyzed by investigations of such sequences via RNAi and Virus Induced Gene Silencing techniques to identify defence genes. For gene expression studies promoter fusions to GUS or Luciferase and analysis via corresponding assays will be carried out. Transformation of the compatible host tobacco with tomato cDNAs should show the responsibility of these genes for the resistance of tomato to C. reflexa attack.