Edlund Erik, Novak Ondrej, Karady Michal, Ljung Karin, Jansson Stefan
Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umeå, 901 87, Sweden.
Laboratory of Growth Regulators, Centre of the Region Haná for Biotechnological and Agricultural Research, Institute of Experimental Botany CAS and Faculty of Science, Palacký University, Šlechtitelů 27, Olomouc, CZ-78371, Czech Republic.
Plant Cell Environ. 2017 May;40(5):622-634. doi: 10.1111/pce.12899. Epub 2017 Mar 27.
Cytokinins are plant hormones that typically block or delay leaf senescence. We profiled 34 different cytokinins/cytokinin metabolites (including precursors, conjugates and degradation products) in leaves of a free-growing mature aspen (Populus tremula) before and after the initiation of autumnal senescence over three consecutive years. The levels and profiles of individual cytokinin species, or classes/groups, varied greatly between years, despite the fact that the onset of autumn senescence was at the same time each year, and senescence was not associated with depletion of either active or total cytokinin levels. Levels of aromatic cytokinins (topolins) were low and changed little over the autumn period. Diurnal variations and weather-dependent variations in cytokinin content were relatively limited. We also followed the expression patterns of all aspen genes implicated as having roles in cytokinin metabolism or signalling, but neither the pattern of regulation of any group of genes nor the expression of any particular gene supported the notion that decreased cytokinin signalling could explain the onset of senescence. Based on the results from this tree, we therefore suggest that cytokinin depletion is unlikely to explain the onset of autumn leaf senescence in aspen.
细胞分裂素是一类植物激素，通常会阻止或延缓叶片衰老。我们连续三年对自由生长的成熟欧洲山杨（Populus tremula）叶片在秋季衰老开始前后的34种不同细胞分裂素/细胞分裂素代谢物（包括前体、缀合物和降解产物）进行了分析。尽管每年秋季衰老的开始时间相同，且衰老与活性或总细胞分裂素水平的消耗无关，但不同年份间单个细胞分裂素种类或类别/组的水平和分布差异很大。芳香族细胞分裂素（托品酮）的水平较低，在秋季期间变化不大。细胞分裂素含量的昼夜变化和天气依赖性变化相对有限。我们还追踪了所有与细胞分裂素代谢或信号传导相关的欧洲山杨基因的表达模式，但无论是任何一组基因的调控模式，还是任何特定基因的表达，都不支持细胞分裂素信号传导减弱可解释衰老开始这一观点。基于这棵树的结果，因此我们认为细胞分裂素消耗不太可能解释欧洲山杨秋季叶片衰老的开始。
