Arora Dhara, Bhatla Satish C
a Laboratory of Plant Physiology and Biochemistry; Department of Botany; University of Delhi ; Delhi , India.
Plant Signal Behav. 2015;10(10):e1071753. doi: 10.1080/15592324.2015.1071753.
Dark-grown sunflower (Helianthus annuus L.) seedlings exhibit modulation of total superoxide dismutase (SOD;EC 1.15.1.1) activity in roots and cotyledons (10,000g supernatant) in response to salt stress (NaCl; 120 mM) through a differential, zymographically detectable, whole tissue activity of FeSOD and Cu/ZnSOD. Confocal laser scanning microscopic imaging (CLSM) has further shown that NaCl stress significantly influences differential spatial distribution of Cu/ZnSOD and MnSOD isoforms in an inverse manner. Dual action of nitric oxide (NO) is evident in its crosstalk with FeSOD and Cu/ZnSOD in seedling roots and cotyledons in control and NaCl(-) stress conditions. Cu/ZnSOD activity in the roots of 2 d old NaCl(-) stressed seedlings is enhanced in the presence of 125-1000 µM of NO donor (sodium nitroprusside; SNP) indicating salt sensitivity of the enzyme activity. Quenching of endogenous NO by cPTIO treatment (500, 1000 µM) lowers FeSOD activity in roots (-NaCl). Cotyledons from control seedlings show an upregulation of FeSOD activity with increasing availability of SNP (125-1000 µM) in the Hoagland irrigation medium. Quenching of NO by cPTIO provides evidence for an inverse correlation between NO availability and FeSOD activity in seedling cotyledons irrespective of NaCl stress. Variable response due to NO on SOD isoforms in sunflower seedlings reflects its concentration-dependent biphasic (pro- and antioxidant) nature of action. Differential induction of SOD isoforms by NO indicates separate intracellular signaling pathways (associated with their respective functional separation) operative in seedling roots as an early salt stress mechanism and in cotyledons as an early long-distance NaCl stress sensing mechanism.
黑暗中生长的向日葵（Helianthus annuus L.）幼苗的根和子叶（10,000g 上清液）中的总超氧化物歧化酶（SOD；EC 1.15.1.1）活性会响应盐胁迫（120 mM NaCl）而发生调节，通过一种可经酶谱检测的、全组织中 FeSOD 和 Cu/ZnSOD 的差异活性来实现。共聚焦激光扫描显微镜成像（CLSM）进一步表明，NaCl 胁迫以相反方式显著影响 Cu/ZnSOD 和 MnSOD 同工型的差异空间分布。在对照和 NaCl（-）胁迫条件下，一氧化氮（NO）在幼苗根和子叶中与 FeSOD 和 Cu/ZnSOD 的相互作用中表现出双重作用。在 125 - 1000 μM 的 NO 供体（硝普钠；SNP）存在下，2 天龄 NaCl（-）胁迫幼苗根中的 Cu/ZnSOD 活性增强，表明该酶活性对盐敏感。用 cPTIO 处理（500、1000 μM）淬灭内源性 NO 会降低根（-NaCl）中的 FeSOD 活性。对照幼苗的子叶显示，随着 Hoagland 灌溉培养基中 SNP 可用性增加（125 - 1000 μM），FeSOD 活性上调。cPTIO 淬灭 NO 为幼苗子叶中 NO 可用性与 FeSOD 活性之间的负相关提供了证据，而与 NaCl 胁迫无关。NO 对向日葵幼苗 SOD 同工型的可变响应反映了其浓度依赖性的双相（促氧化和抗氧化）作用性质。NO 对 SOD 同工型的差异诱导表明，在幼苗根中作为早期盐胁迫机制以及在子叶中作为早期长距离 NaCl 胁迫感知机制，存在单独的细胞内信号通路（与其各自的功能分离相关）在起作用。
