The Dof transcription factor COG1 acts as a key regulator of plant biomass by promoting photosynthesis and starch accumulation

Photosynthetic efficiency is the primary determinant of crop yield,including vegetative biomass and grain yield.Manipulation of key transcription factors known to directly control photosynthetic machinery can be an effective strategy to improve photosynthetic traits.In this study,we identified an Arabidopsis gain-of-function mutant,cogwheel1-3D,that shows a significantly enlarged rosette and increased biomass compared with wild-type plants.Overexpression of COG1,a Dof transcription factor,recapitulated the phenotype of cogwheel1-3D,whereas knocking out COG1 and its six paralogs resulted in a reduced rosette size and decreased biomass.Transcriptomic and quantitative reverse transcription polymerase chain reaction analyses demonstrated that COG1 and its paralogs were required for light-induced expression of genes involved in photosynthesis.Further chromatin immunoprecipitation and electrophoretic mobility shift assays indicated that COG1 can directly bind to the promoter regions of multiple genes encoding light-harvesting antenna proteins.Physiological,biochemical,and microscopy analyses revealed that COG1 enhances photosynthetic capacity and starch accumulation in Arabidopsis rosette leaves.Furthermore,combined results of bioinformatic,genetic,and molecular experiments suggested that the functions of COG1 in increasing biomass are conserved in different plant species.These results collectively demonstrated that COG1 acts as a key regulator of plant biomass by promoting photosynthesis and starch accumulation.Manipulating COG1 to optimize photosynthetic capacity would create new strategies for future crop yield improvement.

SERK Receptor-like Kinases Control Division Patterns of Vascular Precursors and Ground Tissue Stem Cells during Embryo Development in Arabidopsis

During embryo development, the vascular precursors and ground tissue stem cells divide to renew them-selves and produce the vascular tissue, endodermal cells, and cortical cells. However, the molecular mech-anisms regulating division of these stem cells have remained largely elusive. In this study, we show that loss of function of SOMATIC EMBRYOGENESIS RECEPTOR-UKE KINASE (SERK) genes results in aberrant em-bryo development. Fewer cortical, endodermal, and vascular cells are generated in the embryos of serk1 serk2bak1 triple mutants. WUSCHEL-RELATED HOMBOBOX5 (WOXS) is ectopically expressed in vascular cells of serkl serk2 bak1 embryos. The first transverse division of vascular precursors in mid-globular em-bryos and second asymmetric division of ground tissue stem cells in early-heart embryos are abnormally altered to a longitudinal division. The embryo defects can be partially rescued by constitutively activated mitogen-activated protein kinase (MAPK) kinase kinase YODA (YDA) and MAPK kinase MKK5. Taken together, our results reveal that SERK-mediated signals regulate division patterns of vascular precursors and ground tissue stem cells, likely via the YDA-MKK4/5 cascade, during embryo development.

Conserved and differentiated functions of CIK receptor kinases in modulating stem cell signaling in Arabidopsis

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.