Sakai H, Hua J, Chen Q G, Chang C, Medrano L J, Bleecker A B, Meyerowitz E M
Division of Biology, 156-29, California Institute of Technology, Pasadena, CA 91125, USA.
Proc Natl Acad Sci U S A. 1998 May 12;95(10):5812-7. doi: 10.1073/pnas.95.10.5812.
The plant hormone ethylene regulates a variety of processes of growth and development. To identify components in the ethylene signal transduction pathway, we screened for ethylene-insensitive mutants in Arabidopsis thaliana and isolated a dominant etr2-1 mutant. The etr2-1 mutation confers ethylene insensitivity in several processes, including etiolated seedling elongation, leaf expansion, and leaf senescence. Double mutant analysis indicates that ETR2 acts upstream of CTR1, which codes for a Raf-related protein kinase. We cloned the ETR2 gene on the basis of its map position, and we found that it exhibits sequence homology to the ethylene receptor gene ETR1 and the ETR1-like ERS gene. ETR2 may thus encode a third ethylene receptor in Arabidopsis, transducing the hormonal signal through its "two-component" structure. Expression studies show that ETR2 is ubiquitously expressed and has a higher expression in some tissues, including inflorescence and floral meristems, petals, and ovules.
植物激素乙烯调节多种生长和发育过程。为了鉴定乙烯信号转导途径中的组分，我们在拟南芥中筛选乙烯不敏感突变体，并分离出一个显性的etr2-1突变体。etr2-1突变在多个过程中赋予乙烯不敏感性，包括黄化幼苗伸长、叶片扩展和叶片衰老。双突变分析表明ETR2在CTR1的上游起作用，CTR1编码一种与Raf相关的蛋白激酶。我们根据其图谱位置克隆了ETR2基因，发现它与乙烯受体基因ETR1和类ETR1的ERS基因具有序列同源性。因此，ETR2可能在拟南芥中编码第三种乙烯受体，通过其“双组分”结构转导激素信号。表达研究表明，ETR2在各处均有表达，并且在一些组织中具有较高的表达水平，包括花序和花分生组织、花瓣和胚珠。
