Fußeder A, Wartinger A, Hartung W, Schulze E-D, Heilmeier H
Lehrstuhl für Pflanzenphysiologie, Universität Bayreuth, POB 101251, Universitätsstraße 30, D-8580 Bayreuth, F.R.G.
Lehrstuhl für Pflanzenökologie, Universität Bayreuth, POB 101251, Universitätsstraße 30, D-8580 Bayreuth, F.R.G.
New Phytol. 1992 Sep;122(1):45-52. doi: 10.1111/j.1469-8137.1992.tb00051.x.
Xylem sap samples were obtained from one- to four-year-old almond trees [Prunus dulcis (Miller) D. A. Webb] that had been grown in lysimeters of different volumes with different amounts of available water and subjected to an annual drying cycle. The samples were analyzed for cytokinin patterns by ELISA during the growing season. Free bases, ribosides and nucleotides of the N -(Δ -isopentenyl) adenine (iP) and the zeatin (Z) type could be identified and quantified. Z-type cytokinins were always predominant. In many cases the concentrations of the cytokinin fractions were rather constant during the day. In a limited number of days, however, Z-type cytokinins showed peak concentrations in the morning and a rapid decrease in the afternoon. A correlation between water status of the trees and the concentrations of cytokinins or their daily variations in the xylem sap could not be established. When the concentration of abscisic acid in the xylem sap was not limiting leaf conductance, daily-variation of a cytokinin fraction preceded daily variation in leaf conductance. We conclude that in almond trees, cytokinins may affect stomatal behaviour on a short-term basis. This is an outcome of changes in their xylem sap concentrations during the course of a day. Abscisic acid, on the other hand, acts as an opposing signal, the size of which reflects long-term water deficit.
木质部汁液样本取自1至4年生的扁桃树[Prunus dulcis (Miller) D. A. Webb]，这些树种植在不同体积、不同有效水量的蒸渗仪中，并经历年度干旱周期。在生长季节，通过酶联免疫吸附测定法（ELISA）对样本进行细胞分裂素模式分析。可以鉴定并定量N-(Δ-异戊烯基)腺嘌呤（iP）和玉米素（Z）类型的游离碱、核苷和核苷酸。Z型细胞分裂素始终占主导地位。在许多情况下，细胞分裂素组分的浓度在一天中相当稳定。然而，在有限的几天里，Z型细胞分裂素在早晨呈现峰值浓度，下午迅速下降。树木的水分状况与木质部汁液中细胞分裂素的浓度或其每日变化之间未能建立相关性。当木质部汁液中脱落酸的浓度不限制叶片导度时，细胞分裂素组分的每日变化先于叶片导度的每日变化。我们得出结论，在扁桃树中，细胞分裂素可能在短期内影响气孔行为。这是一天中其木质部汁液浓度变化的结果。另一方面，脱落酸作为一种相反的信号，其大小反映长期水分亏缺。
