Exogenous silicon promotes cadmium (Cd) accumulation in Sedum alfredii Hance by enhancing Cd uptake and alleviating Cd toxicity

Ying Hu; Xueqi Zhou; An Shi; Yanshuang Yu; Christopher Rensing; Taoxiang Zhang; Shihe Xing; Wenhao Yang

doi:10.3389/fpls.2023.1134370

Exogenous silicon promotes cadmium (Cd) accumulation in Sedum alfredii Hance by enhancing Cd uptake and alleviating Cd toxicity

Front Plant Sci. 2023 Feb 21:14:1134370. doi: 10.3389/fpls.2023.1134370. eCollection 2023.

Authors

Ying Hu¹, Xueqi Zhou¹, An Shi¹, Yanshuang Yu¹, Christopher Rensing¹, Taoxiang Zhang², Shihe Xing¹, Wenhao Yang¹

Affiliations

¹ Key Laboratory of Soil Ecosystem Health and Regulation of Fujian Provincial University, College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China.
² College of Forestry, Fujian Agriculture and Forestry University, Fuzhou, China.

Abstract

Soil Cadmium (Cd) pollution has become a serious environmental problem. Silicon (Si) plays key roles in alleviating Cd toxicity in plants. However, the effects of Si on mitigation of Cd toxicity and accumulation of Cd by hyperaccumulators are largely unknown. This study was conducted to investigate the effect of Si on Cd accumulation and the physiological characteristics of Cd hyperaccumulator Sedum alfredii Hance under Cd stress. Results showed that, exogenous Si application promoted the biomass, Cd translocation and concentration of S. alfredii, with an increased rate of 21.74-52.17% for shoot biomass, and 412.39-621.00% for Cd accumulation. Moreover, Si alleviated Cd toxicity by: (i) increasing chlorophyll contents, (ii) improving antioxidant enzymes, (iii) enhancing cell wall components (lignin, cellulose, hemicellulose and pectin), (iv) raising the secretion of organic acids (oxalic acid, tartaric acid and L-malic acid). The RT-PCR analysis of genes that involved in Cd detoxification showed that the expression of SaNramp3, SaNramp6, SaHMA2 and SaHMA4 in roots were significantly decreased by 11.46-28.23%, 6.61-65.19%, 38.47-80.87%, 44.80-69.85% and 33.96-71.70% in the Si treatments, while Si significantly increased the expression of SaCAD. This study expanded understanding on the role of Si in phytoextraction and provided a feasible strategy for assisting phytoextraction Cd by S. alfredii. In summary, Si facilitated the Cd phytoextraction of S. alfredii by promoting plant growth and enhancing the resistance of plants to Cd.

Keywords: antioxidant enzyme activity; cell wall; hyperaccumulator; organic acids; silicon.

Grants and funding

This work was financially supported by the National Natural Science Foundation of China (42077132), the Science and Technology project of Fujian Province (No. 2020J01565), the Fundamental Research Funds for the Central Universities (226-2022-00084) and Science and Technology Innovation Fund of Fujian Agriculture and Forestry University (KFb22121XA).