Ca2+参与外源NO诱导增强枇杷幼苗抗冻性的信号转导

Ca2+ involved signal transduction in enhancing frost resistance of loquat seedlings induced by exogenous NO

[目的]从影响枇杷幼苗Ca2信号通路的角度,分析外源Ca2+、钙离子通道抑制剂和钙调素拮抗剂对低温胁迫下幼苗抗氧化能力的影响,探讨Ca2+信号在外源NO诱导增强枇杷幼苗抗冻性中的调控机制.[方法]以2年生的早钟6号枇杷(Eriobotrya Japonica Lindl.cv.Zaozhong No.6)容器苗为试材,采用叶面喷施外源NO供体硝普钠(SNP)、氯化钙(CaCl2)、钙离子通道抑制剂三氯化镧(LaCl3)和钙调素拮抗剂N-(6-氨基己基)-5-氯-1-萘磺胺(W7)处理低温胁迫下的枇杷幼苗,试验共设6个处理,分别为叶面喷施SNP处理(T1)、CaClz+SNP处理(T2)、LaCl3+SNP处理(T3)、W7+ SNP处理(T4)、W7+LaCl3+ SNP处理(T5)以及叶面喷施HzO(对照,CK),研究不同处理对幼苗过氧化氢(H2O2)、丙二醛(MDA)和钙调素(CaM)含量及过氧化氢酶(CAT)、过氧化物酶(POD)、超氧化物歧化酶(SOD)、抗坏血酸过氧化物酶(APX)活性的影响,最后对低温胁迫下枇杷叶片各生理指标的相关性进行了分析.[结果]与对照相比,SNP处理(T1)和CaCl2+ SNP处理(T2)显著促进了叶片细胞CaM含量的增加以及CAT、POD、SOD和APX活性的上升,降低了细胞H2O2和MDA含量,从而减轻了细胞的膜脂过氧化程度,提高了枇杷幼苗的抗冻性.与对照相比,LaCl3+ SNP处理(T3)提高了叶片MDA含量,但是叶片H2O2、CaM含量以及CAT、POD、SOD和APX活性总体均显著降低.与对照相比,W7+ SNP处理(T4)、W7+ LaCl3+ SNP处理(T5)均显著增加了细胞Hz O2和MDA含量,明显降低了叶片细胞CaM含量以及CAT、POD、SOD和APX活性.相关性分析表明,CaM含量与CAT、POD、SOD和APX等保护酶活性的相关系数均高于0.88,呈极显著正相关;而CaM含量与H2 Oz和MDA含量的相关系数分别为-0.721和-0.884,呈极显著负相关;4种保护酶活性与H2 O2和MDA含量之间也呈现极显著负相关.[结论]外源Ca2+和NO具有协同增强枇杷幼苗抗冻性的诱导效应,而LaCl3和W7对外源NO诱导增强枇杷幼苗的抗冻性起阻遏作用,Ca2+参与了外源NO诱导增强枇杷幼苗抗冻性的信号转导.

【Objective】In this study,mediating loquat seedling signal pathway method was used to analyze the effect of exogenous CaCl 2,Ca 2+channel inhibitor and calmodulin antagonist on antioxidant capacity of loquat seedling under low temperature stress.The regulation mechanism of Ca 2+signal pathway to frost resistance of loquat seedling induced by exogenous nitric oxide(NO)was also investigated.【Method】Leaves of two-year-old container seedlings of‘Zaozhong No.6’loquat(Eriobotrya japonica Lindl.)were sprayed with sodium nitroprusside(SNP),calcium chloride(CaCl 2),lanthanum chloride(LaCl 3)and N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide(W7)to investigate the effects on contents of H 2O 2,malondialdehyde(MDA)and calmodulin(CaM)and activities of catalase(CAT),peroxidase(POD),superoxide dismutase(SOD)and ascorbate peroxidase(APX)under low temperature stress.A total of 6 treatments were set in the experiment,including leaf spraying with H 2O(CK),SNP(T1),CaCl 2+SNP(T2),LaCl 3+SNP(T3),W7+SNP(T4),and W7+LaCl 3+SNP(T5).【Result】SNP(T1)and CaCl 2+SNP(T2)treatments increased CaM content and activities of CAT,POD,SOD and APX,while reduced contents of H 2O 2 and MDA,thereby decreased membrane lipid peroxidation level and increased cold resistance of loquat seedling.In comparison,LaCl 3+SNP(T3)treatment increased MDA content of loquat leaves and reduced contents of H 2O 2 and CaM and activities of CAT,POD,SOD and APX.W7+SNP(T4)and W7+LaCl 3+SNP(T5)treatments significantly increased contents of H 2O 2 and MDA and decreased CaM content and activities of CAT,POD,SOD and APX.Correlations of CaM content and protective enzyme activities of CAT,POD,SOD and APX were extremely significant with coefficients of greater than 0.88.Correlations of CaM content with H 2O 2 and MDA were extremely significant and negative with coefficients of-0.721 and-0.884,respectively.There were also significant negative correlations between activities of protective enzymes and contents of H 2O 2 and MDA.【Conclusion】Exogenous Ca 2+and NO had synergistic enhancing role on loquat seedling frost resistance,while the induction and enhancement of loquat seedling frost resistance by exogenous NO were negatively controlled by LaCl 3 and W7.Ca 2+involved in signal transduction in enhancing frost resistance of loquat seedlings induced by exogenous NO.