Abstract: When pea (Pisum sativumL., Alaska strain) was grown in short-day conditions, the apical bud senescence started with the transformation of the bud from vegetative to reproductive growth. DNA fragmentation was detected during the senescence using the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end in situ labeling (TUNEL) method. The cell ultrastructural changes were similar to apoptosis in animal cells: the apical meristemetic cells underwent the programmed cell death (PCD). This was first detected in the apex cells of apical meristem, while peripheral cells differentiated gradually into different parts of a floral bud. But all the cells in the floral bud were subjected to the PCD process before it developed into a complete flower. 140bp DNA fragment was found to deposit in apical bud during the plant development. The most important role of Caspase-8 was detected by Western blot, and the expression of the procaspase-8 was time-related with the DNA frgmentation and the transformation from vegetative to the reproductive growth. These results suggested that PCD was an active process during the differentiation of apical meristem, and the senescence observed in the apical bud was due to the PCD process.

Key words: Pea, apical bud, senescence, programmed cell death(PCD)

摘要： 显微、超微结构研究表明，短日照条件下豌豆顶芽的衰老过程是从营养生长锥向花芽的转化，而用DNA原位末端标记(TUNEL)、Caspase-8 Western Blot和140 bp DNA片断积累的试验结果证明，转化为花芽的整个生长锥细胞发生了编程性死亡(PCD)，而且其最顶端部分细胞首先发生PCD，而顶端周围的分生组织细胞逐渐分化出花芽的各部分，但顶芽最后并没有发育成为完整的花，所有细胞就都发生PCD，从而顶芽衰老。

关键词: 豌豆, 顶芽, 衰老, 细胞编程性死亡(PCD)