Bora Monashree Sarma, Sarma Kali Prasad
Department of Environmental Science, Tezpur University, Napaam, Tezpur, Assam, India.
Department of Environmental Science, Tezpur University, Napaam, Tezpur, Assam, India.
Ecotoxicol Environ Saf. 2021 May 3;218:112285. doi: 10.1016/j.ecoenv.2021.112285.
The present research is an appraisal of anatomical and ultrastructural alterations in aquatic fern, Ceratopteris pteridoides under cadmium (Cd) exposure. Plants were cultured hydroponically for 12 consecutive days in different Cd treatments: 10 µM L (CDT1), 20 µM L (CDT2), 40 µM L (CDT3) and 60 µM L (CDT4). Anatomical and ultrastructural changes of different vegetative tissues of C. pteridoides were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Cd stress significantly (P < 0.05) decreased water content percentage (WC%), relative growth rate (RGR) and root activity in C. pteridoides, especially at highest Cd concentration (treatment CDT4). Significant (P < 0.05) drop of stress tolerance indices (STI) was noticed in C. pteridoides under treatment CDT4. Anatomical study of the Cd-treated C. pteridoides showed stomatal closure of leaves, reduction of diameter in xylem tracheids of stem and root, and decrease of intercellular spaces. Furthermore, ultrastructural alterations of leaf, stem, and root cells were evident with a damaged membrane system of chloroplast and mitochondria, disorganization of chloroplastic components, accumulation of large starch grains and plastoglobules, and formation of multivesicular bodies. The deposition of electron-dense material in the cell wall of root cells can be regarded as an important tolerance mechanism of C. pteridoides under Cd stress. Fourier transform infrared (FTIR) spectroscopy analysis of Cd-treated C. pteridoides biomass illustrated Cd-binding interaction with O-H, N-H, C-H, C≡C, C˭O, P˭O, -C-OH and CS functional groups of different metabolites.
本研究旨在评估水生蕨类植物水蕨（Ceratopteris pteridoides）在镉（Cd）暴露下的解剖学和超微结构变化。将植物在不同镉处理条件下连续水培12天：10微摩尔/升（CDT1）、20微摩尔/升（CDT2）、40微摩尔/升（CDT3）和60微摩尔/升（CDT4）。利用扫描电子显微镜（SEM）和透射电子显微镜（TEM）研究了水蕨不同营养组织的解剖学和超微结构变化。镉胁迫显著（P<0.05）降低了水蕨的含水量百分比（WC%）、相对生长速率（RGR）和根系活力，尤其是在最高镉浓度（处理CDT4）时。在处理CDT4下，水蕨的胁迫耐受指数（STI）显著（P<0.05）下降。对经镉处理的水蕨进行解剖学研究发现，叶片气孔关闭，茎和根的木质部导管直径减小，细胞间隙减小。此外，叶、茎和根细胞的超微结构变化明显，叶绿体和线粒体的膜系统受损，叶绿体成分紊乱，大量淀粉粒和质体小球积累，多泡体形成。根细胞壁中电子致密物质的沉积可被视为水蕨在镉胁迫下的一种重要耐受机制。对经镉处理的水蕨生物量进行傅里叶变换红外（FTIR）光谱分析表明，镉与不同代谢物的O-H、N-H、C-H、C≡C、C˭O、P˭O、-C-OH和CS官能团发生结合相互作用。
