Differentiation processes in the primary root meristem are controlled by several signaling pathways that are regulated by phytohormones or by secreted peptides. Long-term maintenance of an active root meristem require...Differentiation processes in the primary root meristem are controlled by several signaling pathways that are regulated by phytohormones or by secreted peptides. Long-term maintenance of an active root meristem requires that the generation of new stem cells and the loss of these from the meristem due to differentiation are precisely coordinated. Via phenotypic and large-scale transcriptome analyses of mutants, we show that the signaling peptide CLE40 and the recep- tor proteins CLV2 and CRN act in two genetically separable pathways that antagonistically regulate cell differentiation in the proximal root meristem. CLE40 inhibits cell differentiation throughout the primary root meristem by controlling genes with roles in abscisic acid, auxin, and cytokinin signaling. CRN and CLV2 jointly control target genes that promote cell differentiation specifically in the transition zone of the proximal root meristem. While CRN and CLV2 are not acting in the CLE40 signaling pathway under normal growth conditions, both proteins are required when the levels of CLE40 or related CLE peptides increase. We show here that two antagonistically acting pathways controlling root meristem differentiation can be activated by the same peptide in a dosage-dependent manner.展开更多
The shoot apical meristem(SAM)and root apical meristem(RAM)act as pools of stem cells that give rise to aboveground and underground tissues and organs in higher plants,respectively.The CLAVATA3(CLV3)-WUSCHEL(WUS)negat...The shoot apical meristem(SAM)and root apical meristem(RAM)act as pools of stem cells that give rise to aboveground and underground tissues and organs in higher plants,respectively.The CLAVATA3(CLV3)-WUSCHEL(WUS)negative-feedback loop acts as a core pathway controlling SAM homeostasis,while CLV3/EMBRYO SURROUNDING REGION(ESR)40(CLE40)and WUSCHEL-RELATED HOMEOBOX5(WOX5),homologs of CLV3 and WUS,direct columella stem cell fate.Moreover,CLV3 INSENSITIVE KINASES(CIKs)have been shown to be essential for maintaining SAM homeostasis,whereas whether they regulate the distal root meristem remains to be elucidated.Here,we report that CIKs are indispensable for transducing the CLE40 signal to maintain homeostasis of the distal root meristem.We found that the cik mutant roots displayed disrupted quiescent center and delayed columella stem cell(CSC)differentiation.Biochemical assays demonstrated that CIKs interact with ARABIDOPSIS CRINKLY4(ACR4)in a ligand-independent manner and can be phosphorylated by ACR4 in vitro.In addition,the phosphorylation of CIKs can be rapidly induced by CLE40,which partially depends on ACR4.Although CIKs act as conserved and redundant regulators in the SAM and RAM,our results demonstrated that they exhibit differentiated functions in these meristems.展开更多
文摘Differentiation processes in the primary root meristem are controlled by several signaling pathways that are regulated by phytohormones or by secreted peptides. Long-term maintenance of an active root meristem requires that the generation of new stem cells and the loss of these from the meristem due to differentiation are precisely coordinated. Via phenotypic and large-scale transcriptome analyses of mutants, we show that the signaling peptide CLE40 and the recep- tor proteins CLV2 and CRN act in two genetically separable pathways that antagonistically regulate cell differentiation in the proximal root meristem. CLE40 inhibits cell differentiation throughout the primary root meristem by controlling genes with roles in abscisic acid, auxin, and cytokinin signaling. CRN and CLV2 jointly control target genes that promote cell differentiation specifically in the transition zone of the proximal root meristem. While CRN and CLV2 are not acting in the CLE40 signaling pathway under normal growth conditions, both proteins are required when the levels of CLE40 or related CLE peptides increase. We show here that two antagonistically acting pathways controlling root meristem differentiation can be activated by the same peptide in a dosage-dependent manner.
基金the National Natural Science Foundation of China(31770312,31970339,31900166,and 31471402)the 111 Project(B16022)+1 种基金Fundamental Research Funds for the Central Universities(lzujbky-2019-ct04 and lzujbky-2020-kb05)the China Postdoctoral Science Foundation(BX20180133).
文摘The shoot apical meristem(SAM)and root apical meristem(RAM)act as pools of stem cells that give rise to aboveground and underground tissues and organs in higher plants,respectively.The CLAVATA3(CLV3)-WUSCHEL(WUS)negative-feedback loop acts as a core pathway controlling SAM homeostasis,while CLV3/EMBRYO SURROUNDING REGION(ESR)40(CLE40)and WUSCHEL-RELATED HOMEOBOX5(WOX5),homologs of CLV3 and WUS,direct columella stem cell fate.Moreover,CLV3 INSENSITIVE KINASES(CIKs)have been shown to be essential for maintaining SAM homeostasis,whereas whether they regulate the distal root meristem remains to be elucidated.Here,we report that CIKs are indispensable for transducing the CLE40 signal to maintain homeostasis of the distal root meristem.We found that the cik mutant roots displayed disrupted quiescent center and delayed columella stem cell(CSC)differentiation.Biochemical assays demonstrated that CIKs interact with ARABIDOPSIS CRINKLY4(ACR4)in a ligand-independent manner and can be phosphorylated by ACR4 in vitro.In addition,the phosphorylation of CIKs can be rapidly induced by CLE40,which partially depends on ACR4.Although CIKs act as conserved and redundant regulators in the SAM and RAM,our results demonstrated that they exhibit differentiated functions in these meristems.
