J3 regulation of flowering time is mainly contributed by its activity in leaves

Abstract

Multiple genetic pathways coordinately determine the timing of the floral transition from vegetative to reproductive development in response to various endogenous and environmental signals. We have recently reported that a novel flowering promoter, DNAJ HOMOLOG 3 (J3), acts downstream of various floral pathways and mediates the transcriptional regulation of two floral pathway integrators, FLOWRING LOCUS T and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1, through its interaction with a potent flowering repressor, SHORT VEGETATIVE PHASE. Here we show that J3 expression driven by the promoter of SUCROSE TRANSPORTER 2 significantly rescues the late-flowering phenotype of j3-1 loss-of-function mutants, suggesting that J3 activity in leaves mainly contributes to its role in regulating flowering time. Furthermore, we reveal that endogenous expression of J3 requires the cis-element(s) located within J3 coding regions or introns.