Low Temperature Regulatory Circuits and Gene Regulons in Higher Plants

植物对低温的反应差别很大。一个极端是来自热带和亚热带地区的植物，如大豆和水稻，它们在0到12摄氏度的低温下会受到伤害。与之形成鲜明对比的是，来自温带地区的植物不仅具有耐寒性，而且许多植物，如拟南芥和小麦，在暴露于低的非冷冻温度后可以在冷冻中存活下来，这种现象被称为“冷适应”。该项目的总体目标是了解耐寒性的“基因组”基础。具体的重点将是更详细地了解植物如何在改变基因表达方面对低温作出反应。最近在拟南芥中的研究表明，冷驯化涉及包括CBF调控在内的冷调控基因的作用，CBF调控是一组赋予抗冻性并由CBF转录激活子协调调节的基因。该项目将包括三个相关的调查方向。首先，将构建一个低温“接线图”，其中包括低温调节电路及其控制的基因规则的定义。研究的第二步将是确定不同抗冻性植物中低温调控基因的异同。研究的第三条线将是确定拟南芥CBF冷响应途径是否在其他植物中高度保守，以及植物耐寒性的差异是否可以追溯到CBF冷响应途径的差异。比较和功能基因组学方法将用于解决这些问题，包括使用DNA微阵列进行基因表达谱分析。总而言之，这些研究路线将提供对植物进化以应对低温的“基因组机制”的更深入理解，并有可能提供“遗传工具”来提高植物的耐寒性，这些性状具有相当大的农艺和经济重要性。由于CBF调控不仅具有抗冻性，而且还具有抗脱水性，因此本项目的结果也有可能提供遗传工具，以提高重要农业植物的抗旱和耐盐性。可交付成果：微阵列数据和项目的其他信息可在：http://aztec.stanford.edu/cold上找到。

Plants vary greatly in their responses to cold temperatures. At one extreme are plants from tropical and subtropical regions such as soybean and rice, which suffer injury when exposed to chilling temperatures between 0 and 12 degrees Celcius. In sharp contrast, plants from temperate regions are not only chilling tolerant, but many, such as Arabidopsis and wheat, can survive freezing after exposure to low nonfreezing temperatures, a phenomenon known as "cold acclimation." The overall goal of this project is to understand the "genomic" basis of cold tolerance. The specific focus will be to develop a more detailed understanding of how plants respond to low temperature in terms of altering gene expression. This emphasis is motivated by the recent demonstration in Arabidopsis that cold acclimation involves the action of cold-regulated genes including the CBF regulon, a group of genes that imparts freezing tolerance and is coordinately regulated by the CBF transcriptional activators. This project will comprise three related lines of investigation. In the first, a low temperature "wiring diagram" will be constructed that includes a definition of low temperature regulatory circuits and the gene regulons that they control. The second line of investigation will be to determine the similarities and differences of low temperature-regulated genes in plants that differ in freezing tolerance. The third line of investigation will be to determine whether the Arabidopsis CBF cold-response pathway is highly conserved in other plants and whether differences in plant cold tolerance can be traced to differences in CBF cold-response pathways. Comparative and functional genomics approaches will be used to address these issues including gene expression profiling using DNA microarrays. In sum, these lines of investigation will provide a deeper understanding of the "genomic mechanisms" that plants have evolved to cope with low temperature and have the potential to provide "genetic tools" to improve the cold tolerance of plants, traits of considerable agronomic and economic importance. In as much as the CBF regulon not only imparts freezing tolerance, but dehydration tolerance as well, the results of this project also have the potential to provide genetic tools to improve the drought and salinity tolerance of agriculturally important plants.Deliverables:Microarray data and other information about the project can be found at: http://aztec.stanford.edu/cold.