THE MADS-BOX TRANSCRIPTION FACTOR, SOC1, REGULATES MICRORNA MIR156E EXPRESSION TO CONTROL FLOWERING TIME IN ARABIDOPSIS

Abstract

THE TRANSITION FROM VEGETATIVE TO REPRODUCTIVE PHASE IN ANGIOSPERMS IS CONTROLLED BY ENDOGENOUS AND ENVIRONMENTAL SIGNALS. THE MAIN FLOWERING PROMOTION PATHWAYS CONVERGE ON THE UPREGULATION OF TWO FLOWERING PATHWAY INTEGRATORS, FLOWERING LOCUS T (FT) AND SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1), IN ARABIDOPSIS. SOC1 IS EXPRESSED MAINLY IN THE LEAVES AND SAM, AND ITS EXPRESSION INCREASES AS THE PLANT PROCEEDS DURING THE FLORAL TRANSITION. DESPITE EXTENSIVE GENETIC AND MOLECULAR STUDIES, THE MECHANISMS UNDERLYING WHICH SOC1 REGULATES DOWNSTREAM GENES ARE LARGELY UNKNOWN. THROUGH SOC1 CHROMATIN IMMUNOPRECIPITATION FOLLOWED BY TILLING ARRAYS (CHIP-CHIP), WE HAVE SELECTED A MICRORNA GENE, MIR156E, AS A POTENTIAL DOWNSTREAM TARGET OF SOC1 AND CHARACTERIZED HOW SOC1 MEDIATES MIR156E EXPRESSION IN A SPATIAL-TEMPORAL MANNER DURING THE FLORAL TRANSITION. THIS WORK ALLOWS US TO GAIN INSIGHTS TO THE REGULATORY HIERARCHY THAT DETERMINES FLOWERING TIME IN ARABIDOPSIS.