Low Temperature Regulatory Circuits and Gene Regulons in Higher Plants

植物对寒冷温度的反应差异很大。一个极端是来自热带和亚热带地区的植物，如大豆和大米，当暴露在0到12摄氏度的寒冷温度下时，它们会受到伤害。与之形成鲜明对比的是，来自温带地区的植物不仅耐寒，而且许多植物，如拟南芥和小麦，在暴露在非冰冻的低温下后，可以在冰冻中存活下来，这一现象被称为“冷驯化”。该项目的总体目标是了解耐寒的“基因组”基础。具体的重点将是更详细地了解植物如何通过改变基因表达来应对低温。这种重视是因为最近在拟南芥中的研究表明，冷驯化涉及包括CBF调节子在内的冷调节基因的作用，CBF调节子是一组赋予耐寒性的基因，并由CBF转录激活子协调调节。该项目将包括三条相关的调查路线。首先，我们将构建一个低温“接线图”，其中包括低温调节电路及其控制的基因调控基因的定义。第二条线将是确定耐寒性不同的植物中低温调节基因的异同。第三条线将是确定拟南芥CBF冷反应途径在其他植物中是否高度保守，以及植物耐冷性的差异是否可以追溯到CBF冷反应途径的差异。将使用比较基因组学和功能基因组学方法来解决这些问题，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为应对低温而进化的“基因组机制”的更深层次的理解，并有可能提供“遗传工具”来提高植物的耐寒性，这些特征具有相当重要的农学和经济意义。由于CBF调节子不仅赋予抗冻性，而且还赋予脱水耐受性，该项目的结果还有可能提供基因工具，以提高农业重要植物的抗旱性和耐盐性。交付成果：有关该项目的微阵列数据和其他信息，请访问：http://aztec.stanford.edu/cold.

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.