Kim Heejung, Helmbrecht Elizabeth E, Stalans M Blaine, Schmitt Christina, Patel Nesha, Wen Chi-Kuang, Wang Wuyi, Binder Brad M
Department of Biochemistry, Cellular, and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996, USA.
Plant Physiol. 2011 May;156(1):417-29. doi: 10.1104/pp.110.170621. Epub 2011 Mar 8.
Ethylene influences many processes in Arabidopsis (Arabidopsis thaliana) through the action of five receptor isoforms. We used high-resolution, time-lapse imaging of dark-grown Arabidopsis seedlings to better understand the roles of each isoform in the regulation of growth in air, ethylene-stimulated nutations, and growth recovery after ethylene removal. We found that ETHYLENE RECEPTOR1 (ETR1) is both necessary and sufficient for nutations. Transgene constructs in which the ETR1 promoter was used to drive expression of cDNAs for each of the five receptor isoforms were transferred into etr1-6;etr2-3;ein4-4 triple loss-of-function mutants that have constitutive growth inhibition in air, fail to nutate in ethylene, and take longer to recover a normal growth rate when ethylene is removed. The patterns of rescue show that ETR1, ETR2, and ETHYLENE INSENSITIVE4 (EIN4) have the prominent roles in rapid growth recovery after removal of ethylene whereas ETR1 was the sole isoform that rescued nutations. ETR1 histidine kinase activity and phosphotransfer through the receiver domain are not required to rescue nutations. However, REVERSION TO SENSITIVITY1 modulates ethylene-stimulated nutations but does not modulate the rate of growth recovery after ethylene removal. Several chimeric receptor transgene constructs where domains of EIN4 were swapped into ETR1 were also introduced into the triple mutant. The pattern of phenotype rescue by the chimeric receptors used in this study supports a model where a receptor with a receiver domain is required for normal growth recovery and that nutations specifically require the full-length ETR1 receptor.
乙烯通过五种受体亚型的作用影响拟南芥（Arabidopsis thaliana）中的许多过程。我们使用对暗中生长的拟南芥幼苗进行高分辨率、延时成像的方法，以更好地了解每种亚型在空气中生长调节、乙烯刺激的螺旋生长以及乙烯去除后的生长恢复中的作用。我们发现乙烯受体1（ETR1）对于螺旋生长既是必需的也是充分的。使用ETR1启动子驱动五种受体亚型各自的cDNA表达的转基因构建体被转入etr1-6;etr2-3;ein4-4三功能缺失突变体中，这些突变体在空气中具有组成型生长抑制，在乙烯中不能进行螺旋生长，并且在乙烯去除后需要更长时间才能恢复正常生长速率。拯救模式表明，ETR1、ETR2和乙烯不敏感4（EIN4）在乙烯去除后的快速生长恢复中起主要作用，而ETR1是唯一能拯救螺旋生长的亚型。拯救螺旋生长不需要ETR1组氨酸激酶活性和通过接收结构域的磷酸转移。然而，敏感性恢复1（REVERSION TO SENSITIVITY1）调节乙烯刺激的螺旋生长，但不调节乙烯去除后的生长恢复速率。几个将EIN4结构域与ETR1结构域互换的嵌合受体转基因构建体也被导入三突变体中。本研究中使用的嵌合受体的表型拯救模式支持一种模型，即具有接收结构域的受体对于正常生长恢复是必需的，而螺旋生长特别需要全长ETR1受体。
