Cloning And Functional Characterization Of The Circadian Clock Gene OsTOC1 In Rice

Most organisms have evolved circadian clock,an endogenous regulatory mechanism,which is able to predict periodic enviromental changes and efficiently utilize limited resources,so that can increase fitness and therefore be more adaptive.In plants,circadian clock regulates lots of important biological processes,including plant growth,development,flowering,and stress responses.To date,most plant circadian clock studies have focused on the model species Arabidopsis thaliana.However,the molecular mechanisms underlying the circadian clock in crops remain largely unkown,.Therefore,A better understanding of rice circadian system will undoubtedly facilitate breeding and improvement of agronomic traits in rice.In this study,I cloned and characterized OsTOC1,the rice homologous of the Arabidopsis clock genes AtTOC1.Results are as follows.1.I found that OsTOC1 is highly homologous to AtTOC1,and the protein domain of TOC1 is also highly conserved between rice and Arabidopsis.To investigate the functions of OsTOC1,I made OsTOC1 overexpression and RNAi lines driven by Ubi promoter lines,estradiol-induced overexpression lines and RNAi lines,OsTOC1-GFP transgenic lines under the control of OsTOC1 native promoter,and the CRISPR/Cas9 knock-out lines.2.To track rhythms in rice,the Oscab1R::LUC transgenic plants were successfully generated,and used in a fluorescence detection platform to monitor rhythms in rice.3.Unlike in Arabidopsis,the rhythms in rice dampened under the constant light condition,but still maintained under constant dark conditions.4.Similar to Arabidopsis thaliana,the circadian rhythmicity was abolished in the OsTOC1-OE lines.It indicated that OsTOC1 is a core oscillator gene and has a similar function of AtTOC1.5.The OsTOC1-OE lines displayed decreases in grain yield per plant,plant height,1,000-grain weight,and filling rate phenotype compared with wild type.