为探究外源硫化氢(Hydrogen sulfide,H2S)对Cd胁迫下平邑甜茶幼苗根系损伤的影响,及Ca2+在H2S介导重金属胁迫信号传导中的作用,采用营养液培养法,利用外源 Ca2+以及 Ca2+螯合剂 EGTA、质膜 Ca2+通道阻断剂La3+和钙调素拮抗剂CPZ,研究了平邑甜茶幼苗生长、根系细胞死亡、根系活性氧代谢和线粒体特性的变化.结果表明:与单独Cd胁迫处理相比,添加外源Ca2+或H2S供体硫氢化钠(NaSH)均显著缓解了Cd胁迫对平邑甜茶幼苗生长的抑制,根系细胞死亡数量减少,根系超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)活性显著提高,超氧阴离子产生速率(O2-·)、过氧化氢(H2O2)和丙二醛(MDA)含量明显下降,根系线粒体膜透性(MPT)减小,膜电位(Δψm)提高、细胞色素c(Cyt c)含量增加;添加NaSH的同时添加钙离子专一螯合剂EGTA,钙离子通道阻断剂LaCl3或钙调素拮抗剂CPZ抑制了H2S以上的调节作用.可见,外源Ca2+或H2S可稳定线粒体功能,增强活性氧清除能力,减轻Cd对平邑甜茶的伤害,并且在这个过程中H2S缓解Cd胁迫的作用可能依赖于Ca2+.%The purpose of this paper is to explore the effects of hydrogen sulfide(H2S) on root injury of Malus hupehensis Rehd. under Cd stress.The nutrient solution culture was used to study the effects of exogenous Ca2+, EGTA ( Ca2+chelator ),La3+( blocker of Ca2+channel in plasma membrane) and CPZ( antagoniston of calmod-ulin ) on the growth of seedling,root cell death,reactive oxygen species metabolism and mitochondrial properties. The results showed that adding exogenous Ca2+or H2S donor NaSH could obviously alleviate the inhibition to the growth of seedlings,reduced the number of cell death in roots induced by Cd stress;and compared with Cd stress a-lone,the enzymes (SOD,POD,CAT) activities were significantly increased,the rate of superoxide anion production (O2-·),contents of hydrogen peroxide(H2O2)and malondialdehyde(MDA)were significantly decreased,the mitochon-drial membrane permeability(MPT) of root was decreased,the mitochondrial membrane potential(Δψm) of root was increased,the content of cytochrome c(Cyt c) was increased. The alleviative effects of H2S on cadmium injury were inhibited by addition of Ca2+-chelate EGTA,Ca2+channel blocker LaCl3or calmodulin inhibitor CPZ. Those indicate that Ca2+or H2S can stabilize mitochondrial function,enhance the ROS scavenging activity,alleviate the injury of Cd to Malus hupehensis Rehd.,and the effect of H2S on cadmium stress may be dependent on Ca2+in this process.
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