Zheng Hong-Xiang, Yang Yu-Lu, Liu Wen-Shen, Zhong Ying, Cao Yue, Qiu Rong-Liang, Liu Chong, van der Ent Antony, Hodson Martin J, Tang Ye-Tao
School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangdong Provincial Engineering Research Center for Heavy Metal Contaminated Soil Remediation, Sun Yat-sen University, Guangzhou 510006, China.
School of Environmental Science and Engineering, Guangdong Provincial Key Laboratory of Environmental Pollution Control and Remediation Technology, Guangdong Provincial Engineering Research Center for Heavy Metal Contaminated Soil Remediation, Sun Yat-sen University, Guangzhou 510006, China.
J Hazard Mater. 2023 Jun 15;452:131254. doi: 10.1016/j.jhazmat.2023.131254. Epub 2023 Mar 21.
Dicranopteris linearis is the best-known hyperaccumulator species of rare earth elements (REEs) and silicon (Si), capable of dealing with toxic level of REEs. Hence, this study aimed to clarify how D. linearis leaves cope with excessive REE stress, and whether Si plays a role in REE detoxification. The results show that lanthanum (La - as a representative of the REEs) stress led to decreased biomass and an increase of metabolism related to leaf cell wall synthesis and modification. However, the La stress-induced responses, especially the increase of pectin-related gene expression level, pectin polysaccharides concentration, and methylesterase activity, could be mitigated by Si supply. Approximately 70% of the Si in D. linearis leaves interacted with the cell walls to form organosilicon Si-O-C linkages. The Si-modified cell walls contained more hydroxyl groups, leading to a more efficient REE retention compared to the Si-free ones. Moreover, this [Si-cell wall] matrix increased the pectin-La accumulation capacity by 64%, with no effect on hemicellulose-La and cellulose-La accumulation capacity. These results suggest that [Si-pectin] matrix fixation is key in REE detoxification in D. linearis, laying the foundation for the development of phytotechnological applications (e.g., REE phytomining) using this species in REE-contaminated sites.
芒萁是最著名的稀土元素（REEs）和硅（Si）超积累植物物种，能够应对有毒水平的REEs。因此，本研究旨在阐明芒萁叶片如何应对过量的REE胁迫，以及Si是否在REE解毒中发挥作用。结果表明，镧（La - 作为REEs的代表）胁迫导致生物量下降，并增加了与叶细胞壁合成和修饰相关的代谢。然而，Si供应可以减轻La胁迫诱导的反应，特别是果胶相关基因表达水平、果胶多糖浓度和甲酯酶活性的增加。芒萁叶片中约70%的Si与细胞壁相互作用形成有机硅Si-O-C键。与不含Si的细胞壁相比，Si修饰的细胞壁含有更多的羟基，导致更有效地保留REEs。此外，这种[Si-细胞壁]基质使果胶-La积累能力提高了64%，对半纤维素-La和纤维素-La积累能力没有影响。这些结果表明，[Si-果胶]基质固定是芒萁中REE解毒的关键，为在受REE污染的场地利用该物种开发植物技术应用（例如REE植物采矿）奠定了基础。
