Defence reactions during Cuscuta reflexa infection

根和无叶植物寄生虫Cuscuta refexa通过菌丝侵入寄主植物，将水分和营养从寄主转移到寄生植物。葫芦科植物几乎侵染所有草本植物，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，例如幼小的西红柿，能够通过过敏性反应来排斥反射弯曲霉。我们可以证明，作为对葫芦巴接触的响应，番茄改变了局部的Ca~(2+)浓度，并表达了编码细胞壁修饰蛋白的基因。这项拟议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，并开发新的策略来对抗葫芦丝感染。在前期工作中，我们建立了一个番茄消减文库，并对番茄中因反射弯曲霉攻击而上调的基因进行了差异筛选。现在将通过RNAi和病毒诱导的基因沉默技术对这些序列进行分析，以确定防御基因。对于基因表达研究，将进行启动子与GUS或荧光素酶的融合，并通过相应的分析进行分析。将番茄cDNA导入亲和寄主烟草，表明这些基因在番茄对条锈菌侵染的抗性中起着重要作用。

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.