WRKY13 Enhances Cadmium Tolerance by Promoting <i>D-CYSTEINE DESULFHYDRASE</i> and Hydrogen Sulfide Production

Hydrogen sulfide (H₂S), a plant gasotransmitter, functions in the plant response to cadmium (Cd) stress, implying a role for cysteine desulfhydrase in producing H₂S in this process. Whether <i>d</i> <i>-CYSTEINE DESULFHYDRASE</i> (<i>DCD</i>) acts in the plant Cd response remains to be identified, and if it does, how <i>DCD</i> is regulated in this process is also unknown. Here, we report that <i>DCD</i>-mediated H₂S production enhances plant Cd tolerance in Arabidopsis (<i>Arabidopsis thaliana</i>). When subjected to Cd stress, a <i>dcd</i> mutant accumulated more Cd and reactive oxygen species and showed increased Cd sensitivity, whereas transgenic lines overexpressing <i>DCD</i> had decreased Cd and reactive oxygen species levels and were more tolerant to Cd stress compared with wild-type plants. Furthermore, the expression of <i>DCD</i> was stimulated by Cd stress, and this up-regulation was mediated by a Cd-induced transcription factor, WRKY13, which bound to the <i>DCD</i> promoter. Consistently, the higher Cd sensitivity of the <i>wrky13-3</i> mutant was rescued by the overexpression of <i>DCD</i> Together, our results demonstrate that Cd-induced WRKY13 activates <i>DCD</i> expression to increase the production of H₂S, leading to higher Cd tolerance in plants.