一氧化氮参与调控油菜素内酯增强高山离子芥悬浮细胞抗寒性OACSTPCD

In order to investigate whether brassinosteroids(BRs)-induced chilling tolerance is regulated through nitric oxide(NO)signaling molecule,the suspension cultured cells of Chorispora bungeana were treated with 24-epibrassinolide(EBR),NO donor SNP,NO scavenger PTIO,nitric oxide synthase(NOS)inhibitor L-NAME,EBR+PTIO and EBR+L-NAME respectively,and the effects of the above treatments on chilling tolerance,reactive oxygen species(ROS)levels and antioxidant defense system were analyzed in the cells under low temperature stress.The results showed that:(1)exogenous EBR treatment enhanced chilling tolerance in the suspension cultures and alleviated the inhibition of cell viability and aggravations of ion leakage and membrane lipid peroxidation induced by low temperature.The effects of SNP treatment on the above physiological measures were similar to those of EBR.(2)Application of PTIO or L-NAME in combination with EBR significantly decreased cell viability and increased ion leakage and membrane lipid peroxidation in C.bungeana suspension cultures under chilling stress compared with those of EBR treatment alone,suggesting that the block in NO signaling decreased the EBR-enhanced chilling tolerance.(3)EBR treatment further increased NO production and NOS activity in the suspension cells compared with those under chilling stress alone,whereas the EBR-induced NO signal was quenched by the addition of PTIO or L-NAME.(4)Both EBR and SNP obviously inhibited the increases in hydrogen peroxide(H2O2)content,superoxide radical(O·-2)production rate and hydroxyl radical(OH-)content caused by chilling,and remarkably enhanced the activities of ascorbate peroxidase(APX),catalase(CAT),glutathione reductase(GR),peroxidase(POD)and superoxide dismutase(SOD)and contents of ascorbate(AsA)and glutathione(GSH)in the suspension cultured cells,thus alleviating oxidative injury caused by low temperature.However,PTIO and L-NAME blocked the protective effects of EBR.In conclusion,these results suggested that EBR-induced chilling tolerance in C.bungeana suspension cultured cells was through the promotion of NO accumulation by activating NOS activity.EBR might confer an increased tolerance to chilling stress by suppressing the accumulation of ROS caused by chilling and enhancing antioxidant defense system in the suspension cells,both of which were partially regulated by NO signal,resulting in the alleviation of chilling-induced oxidative damage and membrane lipid peroxidation.Thus,NOS-derived NO might be a downstream signaling molecule of EBR signal in C.bungeana suspension cultured cells under low temperature stress.