Ca^(2+)参与外源NO增强低温胁迫下黄瓜幼苗叶片抗氧化能力

Ca^(2+) Involved in Antioxidant Enzymes Activities of Cucumber Seedling Leaves Enhanced by Exogenous Nitric Oxide Under Low Temperature Stress

为探究Ca^(2+)在一氧化氮(NO)增强黄瓜抗氧化能力和耐冷性中的作用,本研究以津研四号黄瓜幼苗为试验材料,通过叶面喷施NO供体亚硝基铁氰化钠(SNP),游离Ca^(2+)螯合剂乙二醇-双-(2-氨基乙基)四乙酸(EGTA),质膜Ca^(2+)通道阻断剂三氯化镧(La Cl3),钙调素(Ca M)活性抑制剂三氟啦嗪(TFP)和钙调素激酶(Ca M-PK)阻断剂N-(6-氨基己基)-5-氯-1-萘磺胺(W-7),研究低温(10℃/6℃)胁迫下黄瓜幼苗叶片相对电导率、丙二醛(MDA)含量、抗氧化酶活性及其相关基因表达量、H_2O_2含量和O_2^(-·)含量的变化。结果表明,与CK相比,水+SNP处理在低温24 h和48 h提高了黄瓜幼苗叶片超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)活性及其相关基因表达,降低了电导率以及MDA和H_2O_2含量,而EGTA+SNP、LaCl_3+SNP、TFP+SNP和W-7+SNP处理抑制了SNP作用效果,表明Ca^(2+)参与NO对低温胁迫下黄瓜幼苗叶片抗氧化过程的调节。此外,在低温0、3和6 h,H_2O_2组织染色显示水+SNP处理的黄瓜幼苗叶片H_2O_2积累量显著高于其他处理;在低温6 h,水+SNP处理黄瓜幼苗叶片O-·2积累量显著高于其他处理,表明活性氧(ROS)可能也作为一种信号分子,位于Ca^(2+)的下游参与NO增强黄瓜幼苗的抗氧化能力。本研究为阐明Ca^(2+)和NO信号系统在提高植物耐冷性中的作用机理提供了理论依据。

In order to explore the role of Ca^（2＋） in antioxidant capacity and cold tolerance of cucumber by nitric oxide（ NO）,Jing Yan NO. 4 cucumber seedlings were selected as experimental materials by spraying NO donor sodium nitroprusside（ SNP）,free Ca^（2＋） chelator glycol-bis-（ 2-amino ethyl ether）-N,N,N＇,N＇-tetraacetic acid（ EGTA）,plasma membrane Ca^（2＋）channel blocker lanthanum trichloride（ LaCl_3）, calmodulin（ Ca M） activity inhibitor trifluoperazine（ TFP） and calmodulin kinase（ Ca M-PK） blocker N-（ 6-aminohexyl）-5-chloro-1-naphthalene sulfonamide（ W-7）,the relative electrical conductivity,malondialdehyde content（ MDA）,antioxidant enzymes and relative gene expression levels,hydrogen peroxide（ H_2O_2） and superoxide anion（ O_2^（-·）） content in the leaves of cucumber seedlings were studied under low temperature stress（ 10℃/6℃）. The results showed pretreatment of water ＋SNP before low temperature could increase the activities of superoxide dismutase（ SOD）,peroxidase（ POD）,catalase（ CAT）,ascorbate peroxidase（ APX） and relative gene expression,while reduce the valued of electrical conductivity,the content of MDA and H_2O_2 tissue staining content of cucumber seedling leaves compared with the control treatment（ CK） under low temperature 24 h and 48 h,but the effects of water ＋ SNP were inhibited by EGTA ＋ SNP,LaCl_3＋SNP,TFP ＋ SNP and W-7 ＋ SNP,suggested that Ca^（2＋）was involved in nitric oxide-induced antioxidant capacity regulation under low tempertate stress. In addition,H_2O_2 accumulation by DAB staining of in leaves of cucumber seedlings of water ＋ SNP treatment were significant higher than the other treatments under the low temperature 0 h,3 h and for 6 h,O_2^（-·） accumulation was significant higher than the other treatments under low temperature for 6 h,indicating reactive oxygen species（ ROS） may also act as a signaling molecule in the downstream of Ca^（2＋） and participate in the enhancement of antioxidant capacity by NO. This study provided a theoretical basis for elucidating the mechanism of Ca^（2＋） and NO signaling system in improving plant cold tolerance.