Molecular Biology of Haustorial Development in Striga asiatica

亚洲独脚金是玉米、高粱、小米和水稻上的主要寄生虫。这种寄生被子植物附着在寄主的根上，并通过一个叫做吸器的特殊器官侵入寄主的维管系统。这种独特结构的发展是由寄生虫对来自宿主的特定化学信号作出反应而开始的。从高粱中分离到一种吸器发育诱导剂，经鉴定为2,6-二甲氧基-对苯醌（2,6- dmbq）。Timko博士建议研究参与吸器诱导和发育的生化和分子遗传机制。利用体内和体外方法的结合，他已经开始定义2,6- dmbq诱导吸器形成后Striga根转录和翻译活性的变化。他将利用从未诱导根、诱导根和成熟吸器中分离的poly(A)+ RNA构建cDNA文库。通过差异筛选程序，他将识别差异表达的基因产物。这些dna的结构特征及其影响寄主植物附着能力和侵入性生长的生化因子的性质。这些研究将为今后的发展阶段提供基础。寄生体与寄主的相互作用为研究植物发育过程的分子控制以及植物与病原体相互作用的分子方面提供了一个独特的机会。了解寄生菌与寄主相互作用的早期事件有助于发展寄生菌和其他根寄生菌的控制方法。

Striga asiatica (witchweed) is a major parasite on corn, Sorghum, millet and rice. This parasitic angiosperm attaches to the host root and invades the host vascular system through a specialized organ termed a haustorium. The development of this unique structure by the parasite is initiated in response to a specific chemical signal from the host. An inducer of Striga haustorial development has been isolated from Sorghum and identified as 2,6- dimethoxy-p-benzoquinone (2,6-DMBQ). Dr. Timko proposes to examine the biochemical and molecular genetic mechanisms involved in haustorial induction and development. Using a combination of in vivo and in vitro approaches he has begun to define the changes in the transcriptional and translational activities of Striga radicles following induction of haustorial formation by 2,6-DMBQ. He will construct cDNA libraries from poly(A)+ RNA isolated from uninduced radicles, induced radicles, and mature haustoria. By differential screening procedures he will identify differentially expressed gene products. These cDNAs will be structurally characterized and the nature of their biochemical factors affecting the development of attachment competency and intrusive growth on host plants. These studies will provide the basis for the future stages of its development. %%% The Striga-host interaction offers an unique opportunity to study the molecular control of plant developmental processes as well as the molecular aspects of plant-pathogen interactions. An understanding of the early events of Striga-host interactions can lead to the development of control methods for Striga and other root parasites.