镉元素是我国农林土壤最严重的重金属污染源。杨树是极具潜力的土壤镉修复植物，但杨树中镉的运输机制尚未清晰，这成为限制镉超累积杨树品种选育的瓶颈。草本植物中DTX家族是一类在植物响应非生物胁迫方面具有重要作用的蛋白家族，但是DTX家族成员参与植物响应镉毒害的机制尚不清楚。申请人前期研究发现毛果杨中PtrDTX1蛋白在拟南芥中过表达可以增强其对镉的毒害应答，而PtrDTX1在酵母细胞中具有运输镉的功能。在此基础上，该项目拟通过针对PtrDTX1的亚细胞定位、组织表达分析、突变体的镉累积特征分析和镉电生理运输功能实验，以及PtrDTX1的上游转录因子筛选与调控机制验证研究等，阐明PtrDTX1在杨树体内向地上部运输镉的分子机制，建立其转录调控模型，为解析DTX家族在运输镉过程中的作用提供分子证据，为将来选育镉超富集杨树品种提供重要依据。

Cadmium (Cd) is one of the most rigorous soil heavy metal contamination for the agriculture and forest of China. Plant growth is serious affected under Cd contamination soils. Populous is a fast-growing woody plant and has great potential to be an important Cd hyperaccumulator. However, the Cd uptake and translocation mechanism remains unclear. Therefore, the present project proposed to characterize the function of putative DTX1 during the Cd uptake and translocation in populus. It’s known that DTX protein family in herbaceous is mainly characterized as a key family involved in response to abiotic stress, such as Aluminum toxicity, plant fungi. However, the function of DTX in response to Cd toxicity is still unknown. In the previous study, we found that PtrDTX1 may be able to transport Cd across yeast vacuole and the expression level of PtrDTX1 was significantly up-regulated under Cd stress condition. Therefore, our present proposal hope to clarify the function of PtrDTX1 for Cd transport in populus by subcellular location analysis, tissue expression analysis, mutant phenotype analysis, Cd transport function analysis etc. And the up-stream transcription factors for PtrDTX1 promoter would be screened and verified. With the above experiments, we hope finally clarify the function of PtrDTX1 and the related regulation model involved in Cd uptake and translocation in populus.