Sulfur reduces the root-to-shoot translocation of arsenic and cadmium by regulating their vacuolar sequestration in wheat (Triticum aestivum L.)

Gaoling Shi; Huan Liu; Dongmei Zhou; Huimin Zhou; Guangping Fan; Wei Chen; Jiangye Li; Laiqing Lou; Yan Gao

doi:10.3389/fpls.2022.1032681

Sulfur reduces the root-to-shoot translocation of arsenic and cadmium by regulating their vacuolar sequestration in wheat (Triticum aestivum L.)

Front Plant Sci. 2022 Oct 5:13:1032681. doi: 10.3389/fpls.2022.1032681. eCollection 2022.

Authors

Gaoling Shi^{1

2

3}, Huan Liu^{1

4}, Dongmei Zhou⁵, Huimin Zhou¹, Guangping Fan¹, Wei Chen¹, Jiangye Li¹, Laiqing Lou⁴, Yan Gao^{1

3}

Affiliations

¹ Key Laboratory of Agro-Environment in Downstream of Yangtze River Plain, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Institute of Agricultural Resources and Environment, Jiangsu Academy of Agricultural Sciences, Nanjing, China.
² School of the Environment and Safety Engineering, Jiangsu University, Zhenjiang, China.
³ Luhe Agro-Environment Experimental Station of National Agricultural Observation and Research Station, Nanjing, China.
⁴ College of Life Sciences, Nanjing Agricultural University, Nanjing, China.
⁵ State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing, China.

Abstract

Accumulation of arsenic (As) and cadmium (Cd) in wheat grain is a serious threat to human health. Sulfur (S) can simultaneously decrease wheat grain As and Cd concentrations by decreasing their translocation in wheat; however, the mechanisms are unclear. We conducted hydroponic experiments to explore the mechanisms by which S modulates As and Cd translocation and their toxicity in wheat. Wheat seedlings were grown in deficient sulfate (2.5 µM) or sufficient sulfate (1.0 mM) nutrient solutions for 6 days and then exposed to zero (control), low As+Cd (1 µM As plus 0.5 µM Cd), or high As+Cd (50 µM As plus 30 µM Cd) for another 6 days. Compared with the control, plant growth was not affected by low As+Cd, but was significantly inhibited by high As+Cd. In the low As+Cd treatment, S supply had no significant effect on plant growth or root-to-shoot As and Cd translocation. In the high As+Cd treatment, sufficient S supply significantly alleviated As and Cd toxicity and their translocation by increasing phytochelatin (PC) synthesis and the subsequent vacuolar sequestration of As and Cd in roots, compared with deficient S supply. The use of _L-buthionine sulfoximine (a specific inhibitor of γ-glutamylcysteine synthetase) confirmed that the alleviation of As and Cd translocation and toxicity in wheat by S is mediated by increased PC production. Also, TaHMA3 gene expression in wheat root was not affected by the As+Cd and S treatments, but the expression of TaABCC1 was upregulated by the high As+Cd treatment and further increased by sufficient S supply and high As+Cd treatment. These results indicate that S-induced As and Cd subcellular changes affect As and Cd translocation mainly by regulating thiol metabolism and ABCC1 expression in wheat under As and Cd stress.

Keywords: TaABCC1; arsenic; cadmium; phytochelatin; subcellular distribution; wheat.