Abstract: Drought is one of the main disastrous weather factors. In this study, we investigated the distributing character of Ca²⁺ in Phyllostachys eduli root tip and the influence mechanism of exogenous Ca²⁺ and its inhibitor under drought stress, by using the laser scanning confocal microscope (LSCM), to explore how the calcium signaling play its role under drought stress. The results showed that calcium ions in apical root cap and elongation zone were more than that in other parts. The total content of intracellular Ca²⁺ increased in about 15 min under treatment with high PEG concentration. The Ca²⁺ accumulated in the cytoplasmic under the high PEG concentration stress, while the accumulation was not obvious under low PEG concentrating stress. The relative electric conductivity (REC), malondialdehyde (MDA) content, catalase (CAT) activity and superoxide dismutase (SOD) activity in Ph. eduli treated by drought stress increased with the treating time. But the POD activity increased firstly and then declined with the time. When the exogenous Ca²⁺ were added, REC and MDA content reduced significantly compared to the control. And the antioxidant enzyme activity gone up, such as POD, SOD and CAT activity. Calcium signaling inhibitors, such as EGTA,heparin,LaCl₃ and CPZ, were able to block conducting system. When the inhibitors were added, REC and MDA contents in the bamboo leaves increased obviously, and the CAT and SOD activities were reduced significantly. These inhibitors, except for EGTA, also cause the POD activity to obviously reduce compared to the control. It was concluded that exogenous Ca²⁺ can promote the resistance of Ph. eduli to draught stress by regulating activities of the protective enzymes.

Key words: Phyllostachys edulis, drought stress, calcium signaling system, the laser scanning confocal microscope(LSCM), antioxidant enzymes