PAT1-type GRAS-domain proteins control regeneration by activating DOF3.4 to drive cell proliferation in Arabidopsis roots

背景回顾：Plant roots possess remarkable regenerative potential owing to their ability to replenish damaged or lost stem cells. ETHYLENE RESPONSE FACTOR 115 (ERF115), one of the key molecular elements linked to this potential, plays a predominant role in the activation of regenerative cell divisions. 

提出问题：However, the downstream operating molecular machinery driving wound-activated cell division is largely unknown. 

主要发现：Here, we biochemically and genetically identified the GRAS-domain transcription factor SCARECROW-LIKE 5 (SCL5) as an interaction partner of ERF115 in Arabidopsis thaliana. 

结果1-SCL5-DOF3.4：Although non-essential under control growth conditions, SCL5 acts redundantly with the related PHYTOCHROME A SIGNAL TRANSDUCTION 1 (PAT1) and SCL21 transcription factors to activate the expression of the DNA-BINDING ONE FINGER 3.4 (DOF3.4) transcription factor gene. 

结果2-DOF3.4-cyclins-再生：DOF3.4 expression is wound-inducible in an ERF115-dependent manner, and in turn activates D3-type cyclin expression. Accordingly, ectopic DOF3.4 expression drives periclinal cell division, while its downstream D3-type cyclins are essential for the regeneration of a damaged root. 

结论：Our data highlight the importance and redundant roles of the SCL5, SCL21 and PAT1 transcription factors in wound-activated regeneration processes and pinpoint DOF3.4 as a key downstream element driving regenerative cell division.

植物的根因其具有补充损伤或丢失的干细胞的能力，从而具有极强的再生潜力。植物根的这种再生潜力其中一个关键分子元件ERF115在激活再生细胞分裂方面发挥重要作用。但是，其下游用于驱动受创伤激活的细胞分裂的分子机制还不清楚。本文中，作者通过生化和遗传试验，鉴定到了一个GRAS结构域转录因子SCL5作为ERF115的互作蛋白，作用于拟南芥的根组织再生。在控制生长条件下，SCL5与PAT1和SCL21转录因子在激活DOF3.4基因的表达上存在功能冗余。DOF3.4基因表达表现出一种依赖于ERF115的创伤诱导模式，进而激活D3型细胞周期蛋白的表达。相应地，异源表达DOF3.4基因会驱动平周细胞分裂，其下游的D3型细胞周期蛋白对于损伤根的再生是必需的。本文的数据揭示了SCL5、SCL21和PAT1转录因子在受创伤激活的再生过程中的重要但冗余作用，同时指出DOF3.4作为一个关键的下游组分，驱动着再生细胞分裂。

** Lieven De Veylder **