The Tartary Buckwheat FtMYB15 Coordinates Cadmium Uptake and Detoxification by Regulating FtZIP3 and FtGSTU19 Expression

ABSTRACT

Tartary buckwheat ( Fagopyrum tataricum ) is a crop of significant value, yet its cultivation in cadmium (Cd)‐contaminated soils poses risks to food safety. Understanding the molecular mechanisms of Cd uptake is crucial for developing strategies to minimize its accumulation. Here, we demonstrate that the Tartary buckwheat transcription factor FtMYB15 promotes Cd ²⁺ influx and enhances Cd accumulation in transgenic hairy roots. Yeast one‐hybrid (Y1H) and electrophoretic mobility shift assay (EMSA) results indicate that FtMYB15 binds to the MYB‐binding sites (MBS) of the FtZIP3 promoter, thereby upregulating the expression of FtZIP3 , which encodes a zinc/iron‐regulated transporter‐like protein. Overexpression of FtZIP3 similarly enhances Cd ²⁺ influx and Cd accumulation in buckwheat hairy roots. Further analysis reveals that FtMYB15 binds to the MBS in the promoter of the tau glutathione S‐transferase gene FtGSTU19 and upregulates its expression in buckwheat hairy roots both before and after Cd exposure. Overexpression of FtGSTU19 in buckwheat hairy roots enhances Cd detoxification capacity via its glutathione transferase activity, thereby alleviating Cd‐induced oxidative stress. Heterologous expression of FtGSTU19 increases Cd tolerance in Arabidopsis . Expression of FtMYB15 , FtZIP3 , and FtGSTU19 is induced by Cd stress. Together, these findings demonstrate that FtMYB15 directly regulates the expression of FtZIP3 and FtGSTU19 , thereby coordinating Cd uptake and detoxification in plants.