Sang Jianrong, Zhang Aying, Lin Fan, Tan Mingpu, Jiang Mingyi
College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China.
Cell Res. 2008 May;18(5):577-88. doi: 10.1038/cr.2008.39.
Using pharmacological and biochemical approaches, the signaling pathways between hydrogen peroxide (H(2)O(2)), calcium (Ca(2+))-calmodulin (CaM), and nitric oxide (NO) in abscisic acid (ABA)-induced antioxidant defense were investigated in leaves of maize (Zea mays L.) plants. Treatments with ABA, H(2)O(2), and CaCl(2) induced increases in the generation of NO in maize mesophyll cells and the activity of nitric oxide synthase (NOS) in the cytosolic and microsomal fractions of maize leaves. However, such increases were blocked by the pretreatments with Ca(2+) inhibitors and CaM antagonists. Meanwhile, pretreatments with two NOS inhibitors also suppressed the Ca(2+)-induced increase in the production of NO. On the other hand, treatments with ABA and the NO donor sodium nitroprusside (SNP) also led to increases in the concentration of cytosolic Ca(2+) in protoplasts of mesophyll cells and in the expression of calmodulin 1 (CaM1) gene and the contents of CaM in leaves of maize plants, and the increases induced by ABA were reduced by the pretreatments with a NO scavenger and a NOS inhibitor. Moreover, SNP-induced increases in the expression of the antioxidant genes superoxide dismutase 4 (SOD4), cytosolic ascorbate peroxidase (cAPX), and glutathione reductase 1 (GR1) and the activities of the chloroplastic and cytosolic antioxidant enzymes were arrested by the pretreatments with Ca(2+) inhibitors and CaM antagonists. Our results suggest that Ca(2+)-CaM functions both upstream and downstream of NO production, which is mainly from NOS, in ABA- and H(2)O(2)-induced antioxidant defense in leaves of maize plants.
采用药理学和生物化学方法，研究了过氧化氢（H₂O₂）、钙（Ca²⁺）-钙调蛋白（CaM）和一氧化氮（NO）在脱落酸（ABA）诱导的玉米（Zea mays L.）植株叶片抗氧化防御中的信号通路。用ABA、H₂O₂和CaCl₂处理可诱导玉米叶肉细胞中NO生成增加以及玉米叶片胞质和微粒体部分一氧化氮合酶（NOS）活性增强。然而，用Ca²⁺抑制剂和CaM拮抗剂预处理可阻断这种增加。同时，用两种NOS抑制剂预处理也抑制了Ca²⁺诱导的NO生成增加。另一方面，用ABA和NO供体硝普钠（SNP）处理也导致叶肉细胞原生质体中胞质Ca²⁺浓度增加以及玉米植株叶片中钙调蛋白1（CaM1）基因表达和CaM含量增加，而用NO清除剂和NOS抑制剂预处理可降低ABA诱导的增加。此外，用Ca²⁺抑制剂和CaM拮抗剂预处理可阻止SNP诱导的抗氧化基因超氧化物歧化酶4（SOD4）、胞质抗坏血酸过氧化物酶（cAPX）和谷胱甘肽还原酶1（GR1）表达增加以及叶绿体和胞质抗氧化酶活性增强。我们的结果表明，在ABA和H₂O₂诱导的玉米植株叶片抗氧化防御中，Ca²⁺-CaM在主要来源于NOS的NO生成的上游和下游均发挥作用。
