Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada.
Nat Chem Biol. 2010 Oct;6(10):741-9. doi: 10.1038/nchembio.435. Epub 2010 Sep 5.
Parasitic weeds of the genera Striga and Orobanche are considered the most damaging agricultural agents in the developing world. An essential step in parasitic seed germination is sensing a group of structurally related compounds called strigolactones that are released by host plants. Although this makes strigolactone synthesis and action a major target of biotechnology, little fundamental information is known about this hormone. Chemical genetic screening using Arabidopsis thaliana as a platform identified a collection of related small molecules, cotylimides, which perturb strigolactone accumulation. Suppressor screens against select cotylimides identified light-signaling genes as positive regulators of strigolactone levels. Molecular analysis showed strigolactones regulate the nuclear localization of the COP1 ubiquitin ligase, which in part determines the levels of light regulators such as HY5. This information not only uncovers new functions for strigolactones but was also used to identify rice cultivars with reduced capacity to germinate parasitic seed.
列当属和独尾草属的寄生杂草被认为是发展中国家最具破坏性的农业因素。寄生种子萌发的一个重要步骤是感应一组结构相关的化合物，称为独脚金内酯，这些化合物是由宿主植物释放的。尽管这使得独脚金内酯的合成和作用成为生物技术的主要目标，但对这种激素知之甚少。利用拟南芥作为平台的化学遗传筛选鉴定出了一系列相关的小分子，即 cotylimides，它们会扰乱独脚金内酯的积累。针对特定 cotylimides 的抑制筛选鉴定出光信号基因是独脚金内酯水平的正调节剂。分子分析表明，独脚金内酯调节 COP1 泛素连接酶的核定位，这在一定程度上决定了光调节剂如 HY5 的水平。这些信息不仅揭示了独脚金内酯的新功能，还用于鉴定出发芽寄生种子能力降低的水稻品种。
