Exogenous selenium enhances cadmium stress tolerance by improving physiological characteristics of Artemisia argyi seedlings

Abstract

The contamination of Chinese medicinal materials with cadmium (Cd) is a pressing global issue that poses significant risks to human health. The beneficial effects of selenium (Se) have been established in improving plant growth and reducing Cd accumulation in plant under Cd stress. This study employed soil cultivation experiments to investigate the remediation effects of exogenous Se (0, 0.5, 1, and 2 mg kg⁻¹) under varying levels of Cd stress (0, 0.6 and 4 mg kg⁻¹). The findings revealed that Cd stress markedly impaired seedling growth, biomass, and physiological characteristics in Artemisia argyi. Regardless of Cd levels, exogenous Se significantly enhanced seedling biomass, improved antioxidant enzyme activity, and increased the plant's antioxidant capacity, thereby mitigating Cd stress. Additionally, exogenous Se promoted A. argyi plant growth, decreased malondialdehyde (MDA) content in the shoots, and under two Cd stress environments of 0.6 and 4 mg kg⁻¹, the application of 1 mg kg⁻¹ Se reduced the Cd content in the aboveground parts of seedlings by 31.99 and 82.21%, respectively. We conclude 1 mg kg⁻¹ Se could represent a promising strategy to contribute to the development and sustainability of crop production on soils contaminated with Cd at a concentration of up to 0.6 and 4 mg kg⁻¹. These results indicate that exogenous Se activates physiological and biochemical defense mechanisms in A. argyi seedlings against Cd stress, offering a foundation for cultivating high-yield, high-quality A. argyi in Cd-contaminated soils.

Keywords: Artemisia argyi; Heavy metal contamination; Oxidative stress; Photosynthesis; Sodium selenite.

Fig. 1

Growth Parameters of A. argyi Under Different Cd and Se Treatments. (a) Plant height; (b) Fresh leaf weight; (c) Dry leaf weight; (d) Dry leaf weight/Fresh leaf weight; (e) Fresh stem weight; (f) Dry stem weight; (g) Dry stem weight/Fresh stem weight. Lowercase letters in the bar graph indicate significant differences among treatments at p < 0.05.

Fig. 2

Cd Content in Different Parts of A. argyi Under Cd and Se Treatments. (a) Cd content in leaves; (b) Cd content in stems; (c) Cd content in the cell wall; (d) Cd content in organelles; (e) Cd content in the cytoplasm; (f) Cd subcellular distribution assays. Lowercase letters in the bar graph indicate significant differences among treatments at p < 0.05.

Fig. 3

Photosynthetic Pigment Content of A. argyi Under Different Cd and Se Treatments. (a) Chlorophyll a content; (b) Chlorophyll b content; (c) Total chlorophyll content; (d) Carotenoid content. Lowercase letters in the bar graph indicate significant differences among treatments at p < 0.05.

Fig. 4

Physiological Indicators of A. argyi Under Different Cd and Se Treatments. (a) SOD content; (b) MDA content; (c) Proline content; (d) Soluble protein content; (e) Soluble sugar content; (f) Reducing sugar content. Lowercase letters in the bar graph indicate significant differences among treatments at p < 0.05.

Fig. 5

Correlation Coefficients of Different Attributes of A. argyi Seedlings Under Se and Cd Treatments. * indicates statistical significance at an adjusted p-value (Bonferroni method) ≤ 0.05. Abbreviations: LFW, leaf fresh weight; LDW, leaf dry weight; SFW, stem fresh weight; SDW, stem dry weight; CHLa, chlorophyll a; CHLb, chlorophyll b; TCHL, total chlorophyll; CH, carotenoids; Cd-L, Cd content in leaves; Cd-S, Cd content in stems; Cd, Cd content in the cell wall; Cd-OR, Cd content in organelles; Cd-SOF, Cd content in the cytoplasm; PRO, proline; SP, soluble protein; SS, soluble sugar; RS, reducing sugar.