2014 Volume 31 Issue 1 Pages 29-34
Many environmental and endogenous factors affect flowering time of plants. In Arabidopsis, there are three major pathways for the control of flowering time; the photoperiod or long-day (LD) pathway, autonomous/vernalization pathway and gibberellic acid (GA) pathway. The flowering regulation under most common photoperiods in Arabidopsis involves some floral activators such as CONSTANS (CO) and GIGANTEA (GI) and a circadian clock protein, EARLY FLOWERING 3 (ELF3). In this work, we examined the effect of ultra-short photoperiod (USP) on flowering time of three accessions (Ler, Col and Ws). All the wild-type plants tested showed remarkable delay of flowering under 3 h or less photoperiods, but different sensitivity to the USP was found in these accessions. Late flowering phenotype of plants with mutations in genes involved in the three major pathways was enhanced under the USP. Expression of FLOWERING LOCUS T (FT) encoding a florigen decreased under the USP. A mutation in the ELF3 gene in Ler largely suppressed the delay of flowering under the USP. These results suggest that floral regulation pathway under the USP may be independent of the three well-characterized pathways. ELF3 may play a key role in the USP pathway.
