Effects of Zn~(2+) on rice root tip cells programmed cell death under high salt stress or UV-induced

Previous study indicated that,the root tip cells of Oryza sativa L.Wuyunjing 8 could be induced to programmed cell death(PCD)by 500 mmol·L-1 NaCl treatment.To investigate the effects of Zn2+ on the PCD of rice root tip cells which was induced by salt stress,tested cells were added with Zn2+ solutions of different concentrations.The results showed that 10 μmol·L-1 Zn2+ could partially inhibit the PCD.The activity of antioxidant enzymes(CAT,APX,POD and SOD)increased rapidly,and then decreased during salt-induced PCD.The addition of Zn2+ increased the activity of antioxidant enzymes,compared with NaCl treatment alone.The observation of H2O2 accumulation in root tip cells showed that the addition of Zn2+ could reduce the H2O2 level and increased the activity of antioxidant enzymes.Zn2+ also inhibited UV-induced PCD in rice root tip cell protoplast.TPEN,a specific chelator of zinc ions,accelerated the PCD process.The results indicated that certain level of Zn2+ inhibits the PCD induced by various stresses in plant cell.