14-3-3s function in plant cadmium response by changes of glutathione and glutathione synthesis in Arabidopsis

Abstract It is well-known that plants respond to the toxin cadmium (Cd), a widespread soil contaminant, by accumulating glutathione (GSH) and phytochelatin (PC). However, the factor(s) in the regulation of GSH and PC synthesis remain to be further identified. Here, we report that 14-3-3 κ and λ negatively regulate plant Cd tolerance because the double mutant 14-3-3κλ with higher Cd accumulation exhibited enhanced Cd tolerance, while overexpressing 14-3-3κ or 14-3-3λ resulted in increased Cd sensitivity in terms of changes of primary root elongation and fresh weight under Cd stress. The expression induction of the genes for GSH and PC synthesis and thus GSH and PC accumulation were further promoted in the 14-3-3κλ mutant but reduced in 14-3-3κ or 14-3-3λ overexpression lines compared with those in the stressed wild-type plants, suggesting the involvement of GSH and PC accumulation in 14-3-3s-mediated plant Cd response. This note was further supported by our observation that higher Cd tolerance was compromised in 14-3-3κλ seedlings treated simultaneously with Cd and buthionine sulfoximine, an inhibitor of GSH synthesis, compared with that in 14-3-3κλ seedlings treated with Cd alone. In addition, Cd-induced ROS accumulation was suppressed in 14-3-3κλ plants but further enhanced in 35S::14-3-3κ and 35S::14-3-3λ transgenic lines compared with that in wild-type plants, in consistent with GSH accumulations in these plants. Together, 14-3-3 s function in plant Cd response by changes of glutathione and glutathione synthesis in Arabidopsis.