Patterson Sara E, Bleecker Anthony B
Department of Horticulture, University of Wisconsin, Madison, Wisconsin 53706, USA.
Plant Physiol. 2004 Jan;134(1):194-203. doi: 10.1104/pp.103.028027. Epub 2003 Dec 30.
Abscission is an important developmental process in the life cycle of the plant, regulating the detachment of organs from the main body of the plant. This mechanism can be initiated in response to environmental cues such as disease or pathogen, or it can be a programmed shedding of organs that no longer provide essential functions to the plant. We have identified five novel dab (delayed floral organ abscission) mutants (dab1-1, dab2-1, dab3-1, dab3-2, and dab3-3) in Arabidopsis. These mutants each display unique anatomical and physiological characteristics and are governed by three independent loci. Scanning electron microscopy shows delayed development of the flattened fracture plane in some mutants and irregular elongation in the cells of the fracture plane in other mutants. The anatomical observations are also supported by breakstrength measurements that show high breakstrength associated with broken cells, moderate levels for the flattened fracture plane, and low levels associated with the initial rounding of cells. In addition, observations on the expression patterns in the abscission zone of cell wall hydrolytic enzymes, chitinase and cellulose, show altered patterns in the mutants. Last, we have compared these mutants with the ethylene-insensitive mutants etr1-1 and ein2-1 to determine if ethylene is an essential component of the abscission process and find that although ethylene can accelerate abscission under many conditions, the perception of ethylene is not essential. The role of the dab genes and the ethylene response genes during the abscission process is discussed.
脱落是植物生命周期中的一个重要发育过程，它调控着器官与植物主体的分离。这种机制可因疾病或病原体等环境信号而启动，也可能是对植物不再具有重要功能的器官进行的程序性脱落。我们在拟南芥中鉴定出了五个新的延迟花器官脱落（dab）突变体（dab1-1、dab2-1、dab3-1、dab3-2和dab3-3）。这些突变体各自表现出独特的解剖学和生理学特征，且受三个独立基因座控制。扫描电子显微镜显示，一些突变体中扁平断裂面的发育延迟，而在其他突变体中，断裂面细胞出现不规则伸长。断裂强度测量结果也支持了解剖学观察，结果表明，与破裂细胞相关的断裂强度较高，扁平断裂面的断裂强度适中，而与细胞初始变圆相关的断裂强度较低。此外，对细胞壁水解酶几丁质酶和纤维素在脱落区表达模式的观察表明，突变体中的表达模式发生了改变。最后，我们将这些突变体与乙烯不敏感突变体etr1-1和ein2-1进行比较，以确定乙烯是否是脱落过程的必要组成部分，结果发现，尽管乙烯在许多情况下可加速脱落，但乙烯感知并非必不可少。本文讨论了dab基因和乙烯反应基因在脱落过程中的作用。
