Selenium Mitigates Cd-Induced Oxidative Stress and Photosynthesis Inhibition in Two Cherry Tomato Cultivars

Abstract

Abstract The purpose of this study is to explore the physiological mechanisms underlying the attenuation of Cd toxicity using Se in two cherry tomato cultivars ‘Hanluzhe’ (HLZ) and ‘Lvfeicui’ (LFC), with low and high Cd accumulation rates, respectively. Hydroponic experiments were conducted and 2.5 μmol L−1 Se was applied to hydroponic solution with 50 μmol L−1 Cd. The photosynthetic parameter, antioxidant enzyme activities, non-enzymatic antioxidants, mineral elements, phytochelatins, and Cd contents of two cherry tomatoes were detected. Exogenous Se reduced Cd assimilation and altered its chemical form and subcellular distribution in both cultivars. Exogenous Se mitigated Cd-induced oxidative stress by enhancing the activity of superoxide dismutase (37.0% in HLZ and 48.9% in LFC), peroxidase (50.6% in HLZ and 30.4% in LFC), catalase (18.5% in HLZ and 28.6% in LFC), ascorbate peroxidase (26.6% in HLZ and 47.4% in LFC), and glutathione peroxidase (28.3% in HLZ and 30.4% in LFC). Although Se significantly increased the photosynthetic rate (Pn) of HLZ, it exhibited no significant effect on the Pn of LFC under Cd stress. Se improved the phytochelatin (15.1% in HLZ and 42.4% in LFC) content, which accelerated Cd chelation in both cultivars. Further, Se alleviated nutrient (Ca, Mg, Fe, Zn, and Cu) assimilation or transportation in both cultivars to varying degrees. The efficiency of Cd toxicity alleviation using Se was higher in the high Cd-accumulating cultivar LFC than in the low Cd-accumulating cultivar HLZ. Screening low Cd-accumulating cultivars with exogenous Se is a promising method to manage Cd accumulation in cherry tomatoes.