Ranjan Plant physiology and Biochemistry Laboratory, Department of Botany, University of Allahabad, Allahabad 211002, India.
Ranjan Plant physiology and Biochemistry Laboratory, Department of Botany, University of Allahabad, Allahabad 211002, India.
Ecotoxicol Environ Saf. 2018 Oct;161:296-304. doi: 10.1016/j.ecoenv.2018.05.052. Epub 2018 Jun 8.
The present study was undertaken to evaluate the metal toxicity alleviating effects of kinetin (KN, 10 nM) on growth, photosynthetic pigments and photochemistry of PS II in the cyanobacterium Nostoc muscorum exposed to chromium (Cr) stress (100 and 150 µM). Chromium declined growth, photosynthetic pigments (chlorophyll a, phycocyanin and carotenoids), photosynthetic oxygen evolution rate and parameters of fluorescence kinetics (ϕP, F/F, ϕE, Ψ and PI except F/F) in concentration dependent manner, while stimulating effects on respiration, energy flux parameters (ABS/RC, TR/RC, ET/RC and DI/RC), oxidative stress biomarkers i.e., superoxide radical (SOR), hydrogen peroxide (HO) and lipid peroxidation (TBARS contents) and antioxidative enzymes: superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and glutathione-S-transferase (GST), were observed. However, upon addition of KN in the growth medium an alleviating effect against chromium induced toxicity on growth, photosynthetic pigments and photochemistry of PS II was recorded. This had occurred due to substantial reduction in levels of oxidative stress biomarkers: SOR, HO and TBARS contents with concomitant rise in activity of antioxidative enzymes: SOD, POD, CAT and GST and appreciable lowering in the cellular accumulation of chromium. The overall results demonstrate that KN application significantly alleviated chromium induced toxicity on growth performance of the cyanobacterium N. muscorum due to significant improvement in photosynthetic pigments and photochemistry of PS II by up-regulating the activity of antioxidative enzymes, and declining cellular accumulation of chromium. Furthermore, Cr induced toxicity at lower dose (100 µM) was found to be ameliorated more efficiently in N. muscorum following supplementation of KN.
本研究旨在评估激动素（KN，10 nM）对铬（Cr）胁迫（100 和 150 µM）下念珠藻生长、光合色素和 PSII 光化学的金属毒性缓解作用。铬以浓度依赖的方式降低了生长、光合色素（叶绿素 a、藻蓝蛋白和类胡萝卜素）、光合放氧速率和荧光动力学参数（除 F/F 外的 ϕP、F/F、ϕE、Ψ和 PI），同时刺激呼吸作用、能量通量参数（ABS/RC、TR/RC、ET/RC 和 DI/RC）、氧化应激生物标志物，即超氧自由基（SOR）、过氧化氢（HO）和脂质过氧化（TBARS 含量）以及抗氧化酶：超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）和谷胱甘肽-S-转移酶（GST）。然而，在生长培养基中添加 KN 可减轻铬对生长、光合色素和 PSII 光化学的毒性。这是由于氧化应激生物标志物水平的显著降低：SOR、HO 和 TBARS 含量，同时抗氧化酶：SOD、POD、CAT 和 GST 的活性升高，以及细胞内铬积累的明显降低。总的来说，这些结果表明，KN 的应用显著缓解了铬对念珠藻生长性能的毒性，这是由于抗氧化酶活性的显著提高，以及细胞内铬积累的减少，从而显著改善了光合色素和 PSII 的光化学。此外，在补充 KN 后，发现念珠藻中较低剂量（100 µM）的 Cr 诱导毒性得到了更有效的改善。
