PyWRKY48 directly activates PyMTP10 to confer cadmium tolerance and accumulation in poplar

Cadmium (Cd) contamination is a major environmental concern that threatens plant growth and human health. Poplar (Populus spp.) is a promising candidate for phytoremediation due to its high biomass, extensive root system and strong capacity for heavy metal tolerance and accumulation. Here, transcriptomic profiling identified PyMTP10 as a critical metal tolerance protein gene that was activated by PyWRKY48 and that encodes a metal tolerance protein, and was strongly induced in PyWRKY48-OE poplar under Cd stress. RT-qPCR further confirmed that PyWRKY48 positively regulates PyMTP10 expression. Yeast one-hybrid, dual-luciferase reporter and electrophoretic mobility-shift assay experiments demonstrated that PyWRKY48 directly binds to the W-box cis-element in the promoter of PyMTP10 and activates its transcription. To investigate the function of PyMTP10, we generated PyMTP10-overexpressing and RNA interference transgenic poplar lines. Under Cd stress, PyMTP10 overexpression improved Cd tolerance, as evidenced by increased growth, chlorophyll content and antioxidant enzyme activities. PyMTP10 overexpression also increased Cd accumulation throughout plant tissues, concomitant with elevated levels of glutathione and phytochelatins. This study revealed that the PyWRKY48-PyMTP10 module coordinately regulates Cd tolerance and accumulation in poplar through the integration of transcriptional activation with enhanced chelation and sequestration. These findings expanded our understanding of Cd detoxification mechanisms in woody plants and provided molecular targets for improving phytoremediation efficiency in Cd-polluted soils.