The transcription factor bZIP44 enhances lead tolerance by activating the expression of PDR12 in Arabidopsis

Lead (Pb) contamination poses a severe threat to plant growth and ecosystem health. Although plants have evolved various detoxification mechanisms, the transcriptional regulation underlying Pb tolerance remains poorly understood. Here, we demonstrate that the transcription factor bZIP44 plays a critical role in mediating Pb stress responses in Arabidopsis. Expression of bZIP44 was induced by Pb stress. The bzip44 mutants showed increased sensitivity to Pb stress and enhanced accumulation of Pb, whereas the bZIP44 overexpression lines were tolerant to Pb stress and reduced Pb accumulation. Further studies revealed that bZIP44 directly binds to the promoter of PDR12, an ABC transporter gene essential for Pb efflux, and activates its expression under Pb stress. Genetic analysis showed that bZIP44 is located upstream of PDR12 and positively regulates the Pb stress response in Arabidopsis. Our findings identify bZIP44 as a key upstream regulator of PDR12 and establish the bZIP44–PDR12 module as a central pathway in Pb detoxification, providing new insights into the molecular mechanisms of heavy metal tolerance in plants.