Zanchin A, Marcato C, Trainotti L, Casadoro G, Rascio N
Department of Biology, Via Trieste 75, University of Padua, 35121 Padova, Italy.
New Phytol. 1995 Feb;129(2):345-354. doi: 10.1111/j.1469-8137.1995.tb04305.x.
Cell wall hydrolases, their mRNAs, and ultrastructural details of cell wall digestion have been studied in peach abscission zones (AZ) located at the base of flower bud (AZ1) and the base of flower receptacle (AZ2), respectively. Induction of abscission was obtained by treatment of explants with exogenous ethylene. Cell separation patterns of the two examined abscission zones have been compared with those of other already known AZs of peach, i.e. the AZs located between fruit and peduncle and the leaf AZ. Analyses have shown similarities in response to ethylene treatment between AZ1 and leaf AZ and between AZ2 and AZs, respectively. Results have been discussed considering the precise position of AZ1 and AZ2 on the flower bud. The timing of functional differentiation, evaluated as the cells'ability to respond to induction by ethylene treatments, showed that AZ1 and AZ2 became functional after bud breaking and bud scale shedding. Later on, they lost their functionality at about 6-7 wk from anthesis. AZ3 became functional very precociously and could be activated 1 wk after anthesis in the fertilized flowers. In the latter zone the cells could also undergo a morphological predifferentiation, even though it occurred a long time after the acquisition of the ethylene responsiveness. This finding shows that morphological differentiation is not necessarily a prerequisite for those cells to become competent to respond to the abscission inducing stimuli.
分别在位于花芽基部（AZ1）和花托基部（AZ2）的桃脱落区，研究了细胞壁水解酶、它们的信使核糖核酸以及细胞壁消化的超微结构细节。通过用外源乙烯处理外植体来诱导脱落。已将两个被检查脱落区的细胞分离模式与桃的其他已知脱落区，即位于果实与果梗之间的脱落区和叶片脱落区的模式进行了比较。分析表明，AZ1与叶片脱落区以及AZ2与其他脱落区之间，在对乙烯处理的反应上分别存在相似性。已结合AZ1和AZ2在花芽上的精确位置对结果进行了讨论。以细胞对乙烯处理诱导的反应能力来评估功能分化的时间，结果表明，AZ1和AZ2在芽萌发和芽鳞片脱落之后开始发挥功能。之后，在开花后约6 - 7周它们失去功能。AZ3非常早熟地开始发挥功能，在受精花开花后1周即可被激活。在后一个脱落区，细胞也可能经历形态学预分化，尽管这发生在获得乙烯反应能力很久之后。这一发现表明，形态学分化不一定是这些细胞具备对脱落诱导刺激作出反应能力的先决条件。
