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.

The association of HpDof1.7 and HpDof5.4 with soluble sugar accumulation in pitaya fruit by transcriptionally activating sugar metabolic genes

Soluble sugar is one of the most important factors affecting fruit flavor and quality.Here,we report the identification of two Dof(DNA-binding with one finger)transcription factors termed HpDof1.7 and HpDof5.4 and their roles in influencing sugar accumulation in pitayas.HpDof1.7 and HpDof5.4 share a similar expression pattern with sugar metabolism-related genes HpSuSy1 and HpINV2,and sugar transporter genes HpTMT2 and HpSWEET14 during pitayas maturation,and their expression pattern was also consistent with the accumulation of glucose and fructose,which were the predominant sugars in pitayas.HpDof1.7 and HpDof5.4 were both typical nucleus-localized proteins with trans-activation ability.Gel mobility shift assay revealed that HpDof1.7 and HpDof5.4 were bound to promoters of HpSuSy1,HpINV2,HpTMT2 and HpSWEET14.Finally,transient expression assays in tobacco leaves showed that HpDof1.7 and HpDof5.4 increased the activities of HpSuSy1,HpINV2,HpTMT2 and HpSWEET14 promoters,thus facilitating sugar accumulation by transcriptionally enhancing sugar metabolic pathway genes.Our findings provide a new perspective on the regulatory mechanisms of Dof transcription factors in sugar accumulation and pitaya fruit quality formation.