The YDA-MKK4/MKK5-MPK3/MPK6 Cascade Functions Downstream of the RGF1-RGI Ligand-Receptor Pair in Regulating Mitotic Activity in Root Apical Meristem

• 作者: Yiming Shao Xinxing Yu Xuwen Xu Yong Li Wenxin Yuan Yan Xu Chuanzao Mao Shuqun Zhang Juan Xu
• 来源期刊: 分子植物（英文版）
• 年，卷（期）: 2020,（11）
• 所属期刊栏目: Research Articles
• 页码范围: 1608-1623
• 页数: 16页
• 语种: 英文

摘要

The mitotic activity of root apical meristem(RAM)is critical to primary root growth and development.Pre-vious studies have identified the roles of ROOT GROWTH FACTOR 1(RGF1),a peptide ligand,and its recep-tors,RGF1 INSENSITIVEs(RGIs),a clade of five leucine-rich-repeat receptor-like kinases,in promoting cell division in the RAM,which determines the primary root length.However,the downstream signaling com-ponents remain elusive.In this study,we identify a complete mitogen-activated protein kinase(MAPK or MPK)cascade,composed of YDA,MKK4/MKK5,and MPK3/MPK6,that functions downstream of the RGF1-RGI ligand-receptor pair.Similar to the rgi1/2/3/4/5 quintuple mutant,loss-of-function mutants of MPK3 and MPK6,MKK4 and MKK5,or YDA show a short-root phenotype,which is associated with reduced mitotic activity and lower expression of PLETHORA 1(PLT1)/PLT2 in the RAM.Furthermore,MPK3/MPK6 activation in response to exogenous RGF1 treatment is impaired in the rgi1/2/3/4/5 quintuple,yda single,and mkk4 mkk5 double mutants.Epistatic analyses demonstrated that the expression of constitutively active MKK4,MKK5,or YDA driven by the RGI2 promoter can rescue the short-root phenotype of the rgi1/2/3/4/5 mutant.Taken together,these results suggest that the YDA-MKK4/MKK5-MPK3/MPK6 cascade functions downstream of the RGF1-RGI ligand-receptor pair and upstream of PLT1/PLT2to modu-late the stem cell population and primary root growth in Arabidopsis.