Abstract: Senescence is the process of programmed degradation. The G2 line of pea exhibits apical senescence-delaying phenotype under short-day (SD) conditions, but the mechanism regulating the apical senescence is still largely unknown. Gibberellin (GA) was proved to be able to delay this apical senescence phenotype in G2 pea grown under long-day (LD) conditions. Here we show that the initiation of cell death signals in the terminal floral meristem was involved in the regulation of apical senescence in pea plants. SD signals prevented the formation of the cell death region in the apical mersitem. Moreover, GA3 treatment could effectively inhibit the occurrence of cell death-mediated apical senescence in LD-grown apical buds. Therefore, our data suggest that the prevention of apical senescence in SD-grown G2 pea through GA3 treatment may be largely responsible for the regulation of occurrence of the DNA fragmentation in apical meristem.

Key words: apical senescence, cell death, gibberellin, photoperiod, Pisum G2.