Abstract
In Arabidopsis, phyB, cry2 and phyA are important photoreceptors for flowering regulation. Recent reports have demonstrated that these photoreceptors regulate stability of CO protein and FT gene expression. However, how these photoreceptors regulate FT expression is still unclear.
We found that a T-DNA insertion line (SALK) exhibited dramatic late flowering phenotype under continuous white light and named it as the tdu mutant. The tdu mutant showed low FT expression and late flowering phenotype, although CO expression was normal. Analyses of several alleles, overexpressors and silencing lines demonstrated that the gene into which T-DNA was inserted was indeed the causal gene. The TDU gene encodes a novel nuclear protein containing glutamine-rich region, which is often seen in transcription activators. Homologues of TDU are found in other plant species. Moreover, analyses of hypocotyl elongation, flowering time under monochromatic light and genetic analyses suggested that TDU functions downstream of cry2.
