关键词: 豌豆, 顶芽, 衰老, 细胞编程性死亡(PCD)

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)