拟南芥VEW1转录因子调控镉胁迫响应的分子机制

An Arabidopsis cadmium (Cd)-resistant vew1-1D mutant was identified in a screen for the XVE-tagging T-DNA insertion lines. VEW1 gene was cloned by using Tail-PCR and shown to encode an unkown functional WRKY transcription factor. Our preliminary studies showed that Arabidopsis VEW1 transcription factor might regulate Cd tolerance by directly activating transcription of AtPDR8 gene, which encodes a Cd2+ extrusion pump. Moreover, an unfunctional VEW1-interacting protein VIP1 was also identified by using a yeast two-hybrid system, and loss-of-function of VIP1 resulted in enhanced Cd resistance. Based these results, we postulated that VIP1 might interact with VEW1 to regulate Cd resistance by modulating VEW1-activated AtPDR8 expression in Arabidopsis. In this work, we will further study the function of VEW1 in reguting Cd resistance, confirm the interaction of VEW1 and VIP1 as well as its effect on expression of the downstream gene AtPDR8, clarify the VEW1-mediated signaling pathway, and uncover the molecular mechanisms mediated by VEW1 in response to Cd stress. These results will provide not only new insights into understanding the mechanisms involved in tolerance of plants to Cd stress but also the novel candidate gene for its application in the improvement of quality in crops.

从化学诱导型启动子激活标记系统构建的拟南芥突变体库中分离了一个对镉（Cd）胁迫耐受的突变体 vew1-D。利用Tail-PCR等技术克隆了VEW1基因，其编码一个WRKY家族中功能未知的转录因子。初步研究表明，VEW1可能通过激活编码Cd2+离子泵的AtPDR8基因转录来调控植物对Cd胁迫的耐受性；此外，利用酵母双杂系统鉴定了一个功能未知的与VEW1互作蛋白VIP1，其功能缺失导致植株对Cd胁迫耐受增加。据此推测：VIP1可能通过与VEW1互作来调节AtPDR8基因表达进而控制植物对Cd胁迫的耐受性。本项目拟进一步探讨VEW1基因功能，研究VEW1与VIP1互作及其对下游靶基因AtPDR8的调控作用，解析其信号转导途径，阐明其调控植物对Cd胁迫响应的分子机理。该研究不仅有助于揭示植物对重金属胁迫响应的信号转导机制，而且可为农作物品质遗传改良提供新的基因资源。

从化学诱导型启动子激活标记系统构建的拟南芥突变体库中，鉴定了一个耐受镉（Cd）毒害的突变体vew1-D。利用Tail-PCR、DNA测序及BLAST分析及转基因功能验证等技术克隆了VEW1基因。该基因编码一个WRKY转录因子，定位于细胞核内。VEW1基因被Cd诱导表达。VEW1基因过表达导致植株Cd含量降低和耐受，而VEW1功能缺失则导致植株Cd积累增加和敏感。进一步分析发现在Cd胁迫过程中VEW1转录因子调控一个编码Cd2+离子泵的AtPDR8基因的转录；此外，还发现VEW1基因过量表达也导致了Cd胁迫相关基因表达。这些结果表明，VEW1基因主要通过激活AtPDR8基因转录来降低Cd含量从而增加植株对Cd的耐受性。该研究不仅揭示了植物耐受Cd毒害的新机制，而且为从源头上控制食品安全提供了新的技术途径和基因资源。由于研究期限为1年，因此相关内容还在深入研究中。目前已在New Phytologist上发表基金标注论文1篇，申请发明专利1项，培养研究生4人，待发表论文1-2篇。