Abstract
Cadmium (Cd) pollution in food chains pose a potential health risk for humans. Sulfur (S) is a significant macronutrient that plays a significant role in the regulation of plant responses to diverse biotic and abiotic stresses. However, no information is currently available about the impact of S application on ascorbate-glutathione metabolism (ASA-GSH cycle) of Pakchoi plants under Cd stress. The two previously identified genotypes, namely, Aikangqing (a Cd-tolerant cultivar) and Qibaoqing (a Cd-sensitive cultivar), were utilized to investigate the role of S to mitigate Cd toxicity in Pakchoi plants under different Cd regimes. Results showed that Cd stress inhibited plant growth and induced oxidative stress. Exogenous application of S significantly increased the tolerance of Pakchoi seedlings suffering from Cd stress. This effect was demonstrated by increased growth parameters; stimulated activities of the antioxidant enzymes and upregulated genes involved in the ASA-GSH cycle and S assimilation; and by the enhanced ASA, GSH, phytochelatins, and nonprotein thiol production. This study shows that applying S nutrition can mitigate Cd toxicity in Pakchoi plants which has the potential in assisting the development of breeding strategies aimed at limiting Cd phytoaccumulation and decreasing Cd hazards in the food chain.
Highlights
Heavy metal contamination in the soil has become a severe environmental problem worldwide and has attracted considerable attention [1,2,3,4]
Cd stress decreased the growth parameters of both cultivars compared with the control (Figure 1)
The suppression effects of Cd stress on growth characters were stronger in Qibaoqing than those in Aikangqing
Summary
Heavy metal contamination in the soil has become a severe environmental problem worldwide and has attracted considerable attention [1,2,3,4]. Among the toxic heavy metals, Cadmium (Cd) is recognized as one of the major widespread environmental pollutants and highly toxic to plants and humans, affecting their growth and health [5,6,7]. Some studies have demonstrated that oxidative stress is a major component of Cd phytotoxicity [12,13] and mediates cellular damage [6]. Under this condition, plants have evolved a list of complex metabolic strategies to counterbalance toxicity due to Cd stress [3]. Some of these strategies are cellular wall binding [14,15], plasma membrane pumping, restriction of uptake and transport [16,17], extra- and intracellular chelation, sequestration in vacuoles [18], antioxidant system composed of enzymatic and non-enzymatic components, and signaling mechanisms [19,20]
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