Verma Nidhi, Pandey Aparna, Tiwari Santwana, Prasad Sheo Mohan
Ranjan Plant Physiology and Biochemistry Laboratory, Department of Botany, University of Allahabad, Prayagraj - 211002 India.
Biochem Biophys Rep. 2021 Feb 13;26:100953. doi: 10.1016/j.bbrep.2021.100953. eCollection 2021 Jul.
Calcium (Ca) and nitric oxide (NO) are potentially active and multitasking signaling molecules which are known to regulate abiotic stresses in plants, but their interactive role in the acquisition of metal stress tolerance in cyanobacteria remains elusive. In current study the signaling role of Ca (800 μM) and NO (10 μM SNP) on key physiological and biochemical attributes of the agriculturally and economically important cyanobacterium ATCC 27893 subjected to Ni stress (2 μM) was examined. Results revealed that Ni at elevated level caused severe damages to the test organism but exogenous supplementation of Ca and NO efficiently mitigated its toxic effects and up-regulated the growth, pigment contents, rate of photosynthesis (whole cell oxygen evolution and Chl fluorescence indices: Kinetic traits: ΦP Ψ, ΦE and PI, along with Fv/F), nitrogen metabolism (NO‾ and NO‾ uptake, nitrate:NR and NiR; and ammonia:GS and GOGAT; assimilating enzymes), and boosted the enzymatic (SOD, POD, CAT and GST) along with non-enzymatic (proline, cysteine and NP-SH) antioxidants. Whereas the increased values of energy flux traits: (ABS/RC, TR/RC, DI/RC and ET/RC) along with F/Fv, rate of respiration, oxidative stress biomarkers (SOR, HO and MDA), and activity of GDH enzyme exhibited lowering trends with application of Ca and NO. Further, addition of EGTA (Ca scavenger) and PTIO (NO scavenger) reversed the positive impacts of Ca and NO and worsened the toxicity of Ni on test cyanobacterium, but the damages were more pronounced under PTIO application that demonstrated Ca mediated signaling role of NO in Ni toxicity alleviation.
钙（Ca）和一氧化氮（NO）是具有潜在活性的多任务信号分子，已知它们可调节植物中的非生物胁迫，但其在蓝藻中获得金属胁迫耐受性方面的相互作用仍不清楚。在当前研究中，研究了钙（800 μM）和NO（10 μM SNP）对遭受镍胁迫（2 μM）的具有农业和经济重要性的蓝藻ATCC 27893的关键生理和生化特性的信号作用。结果表明，高水平的镍对受试生物造成了严重损害，但外源补充钙和NO有效减轻了其毒性作用，并上调了生长、色素含量、光合作用速率（全细胞放氧和叶绿素荧光指数：动力学特征：ΦP Ψ、ΦE和PI，以及Fv/F）、氮代谢（NO‾和NO‾吸收、硝酸盐：NR和NiR；以及氨：GS和GOGAT；同化酶），并增强了酶促（SOD、POD、CAT和GST）以及非酶促（脯氨酸、半胱氨酸和NP-SH）抗氧化剂。而能量通量特征值（ABS/RC、TR/RC、DI/RC和ET/RC）以及F/Fv、呼吸速率、氧化应激生物标志物（SOR、HO和MDA）和GDH酶活性随着钙和NO的应用呈下降趋势。此外，添加EGTA（钙清除剂）和PTIO（NO清除剂）逆转了钙和NO的积极影响，并加剧了镍对受试蓝藻的毒性，但在PTIO应用下损害更为明显，这表明NO在缓解镍毒性方面具有钙介导的信号作用。
