The DoGST18-DoHSP70 module modulates the cadmium tolerance of Dendrobium officinale

Dendrobium officinale is a well-known traditional Chinese medicinal plant in Orchidaceae, and cadmium (Cd) toxicity in the substrate of continuous cultivation has become an important factor limiting cultivation of D. officinale domesticated seedling. Glutathione S-transferase (GSTs) are well-characterized as crucial mediators of plant stress responses. However, their specific functional roles and molecular mechanisms in Cd tolerance remain poorly understood in D. officinale. In this study, we identified a member of the GST gene family, DoGST18, demonstrating its significant involvement in Cd detoxification. DoGST18 expression in yeast increased host tolerance to Cd. In addition, genetic transformation in Arabidopsis revealed that overexpression (OE) lines exhibited enhanced Cd resistance relative to wild-type lines, as evidenced by growth rates and antioxidant enzyme activities. The candidate target S5M5N9/DoHSP70 was identified by pull-down and mass spectrometry. Yeast two-hybrid, bimolecular fluorescence complementation and co-immunoprecipitation experiments confirmed the specific interaction between DoGST18 and S5M5N9 in the plant cytoplasm, which was also proved by further pull-down experiments. Our findings offer a crucial theoretical foundation for revealing the molecular mechanism of DoGST18 in the Cd resistance of D. officinale, and will potentially contribute to cultivating low Cd-accumulating D. officinale germplasm.