Effect of Selenium Application on Growth, Antioxidative Capacity, and Nutritional Quality in Purple Lettuce Seedlings

Selenium (Se) is involved in the growth and development of plants. More importantly, Se from plant foods is a primary source of Se intake for humans and animals. Improving the Se content in vegetables through biofortification is an effective way to solve the hidden hunger induced by Se deficiency. This study demonstrated the effect of different exogenous Se application concentrations on the growth, antioxidative capacity, and nutritional quality of purple lettuce (Lactuca sativa var. crispa L. "Purple Rome") at the seedling stage. The low Se application concentration (& LE;8 & mu;M) significantly promoted the lettuce seedling growth. Conversely, the high Se application concentration (16 & mu;M) inhibited the seedling growth and overproduced the reactive oxygen species in lettuce root tips, which caused oxidative damage to membrane lipids and cell death. Furthermore, the enzyme activities and gene expression of the antioxidant enzymes, superoxide dismutase-peroxidase, and catalase, were significantly increased under exogenous Se application. The exogenous Se application significantly increased the accumulation of nutrients in purple lettuce at the seedling stage. Remarkably, the exogenous Se application concentrations were significantly positively related to the Se and anthocyanin contents. The gene expression levels of chalcone synthase were positively correlated with the anthocyanin contents under exogenous Se application. This study contributes to the role of Se in lettuce growth and provides a reference for producing high-quality purple lettuce rich in Se and anthocyanins.