Zentgraf U, Jobst J, Kolb D, Rentsch D
Centre of Molecular Biolology of Plants, University of Tübingen, Tübingen, Germany.
Plant Biol (Stuttg). 2004 Mar-Apr;6(2):178-83. doi: 10.1055/s-2004-815735.
Senescence is a form of programmed cell death (PCD) which leads to the death of whole organs, e.g., leaves or flowers, and eventually to the death of entire plants. Like all forms of PCD, senescence is a highly regulated and energy consuming process. Senescence parameters, like protein content, chlorophyll content, expression of photosynthesis-associated genes or senescence-associated genes (SAGs), reveal that senescence occurs in old leaves derived from young plants (6 week old) as well as in young leaves derived from older plants (8 week old), indicating that it is governed by the actual age of the leaves. In order to analyse the differential gene expression profiles during leaf senescence, hybridizations of high-density genome arrays were performed with: i) individual leaves within the rosette of a 6-week-old plant and ii) leaves of the same position within the rosette but harvested from plants of different ages, ranging from 5 to 8 weeks. Cluster and genetree analyses, according to the expression pattern revealed that genes which are up-regulated with respect to the age of the entire plant, showed completely different expression profiles with respect to the age of the individual leaves within one rosette. This was observed even though the actual difference in leaf age was approximately the same. This indicates that gene expression appears to be governed by different parameters: i) the age of the individual leaf and ii) the age and developmental stage of the entire plant.
衰老 是程序性细胞死亡（PCD）的一种形式，它会导致整个器官（如叶片或花朵）死亡，并最终致使整株植物死亡。与所有形式的PCD一样，衰老是一个高度受调控且耗能的过程。衰老参数，如蛋白质含量、叶绿素含量、光合作用相关基因或衰老相关基因（SAGs）的表达，表明衰老既发生在幼龄植物（6周龄）长出的老叶中，也发生在老龄植物（8周龄）长出的幼叶中，这表明衰老受叶片的实际年龄控制。为了分析叶片衰老过程中的差异基因表达谱，使用以下材料进行了高密度基因组阵列杂交：i）6周龄植物莲座叶丛中的单片叶子，以及ii）莲座叶丛中相同位置但从5至8周龄不同年龄的植物上收获的叶子。根据表达模式进行的聚类和基因树分析表明，相对于整株植物的年龄上调的基因，在莲座叶丛中相对于单片叶子的年龄显示出完全不同的表达谱。即便叶片年龄的实际差异大致相同，也观察到了这种情况。这表明基因表达似乎受不同参数控制：i）单片叶子的年龄，以及ii）整株植物的年龄和发育阶段。
