Abstract
The Bromeliaceae family is one of the most morphologically diverse families with a pantropical distribution. To schedule an appropriate flowering time for bromeliads, ethylene is commonly used to initiate flower development in adult plants. However, the mechanism by which ethylene induces flowering in adult bromeliads remains unknown. Here, we identified an APETALA2 (AP2)-like gene, AfAP2-1, in Aechmea fasciata. AfAP2-1 contains two AP2 domains and is a nuclear-localized protein. It functions as a transcriptional activator, and the activation domain is located in the C-terminal region. The expression level of AfAP2-1 is higher in juvenile plants than in adult plants, and the AfAP2-1 transcript level was rapidly and transiently reduced in plants treated with exogenous ethylene. Overexpression of AfAP2-1 in Arabidopsis thaliana results in an extremely delayed flowering phenotype. These results suggested that AfAP2-1 responds to ethylene and is a putative age-dependent flowering regulator in A. fasciata.
Highlights
The Bromeliaceae family, which consists of 3248 species in 58 genera [1,2], is one of the most morphologically diverse families with a pantropical distribution [3]
Five genetic pathways relevant to flowering have been identified in the model species Arabidopsis thaliana, namely, the photoperiod, vernalization, gibberellic acid, autonomous and ageing pathways [9]. During this complex developmental process, a subset of flowering-promoter and -suppressor genes participate in multiple pathways, such as APETALA2 (AP2) and five other AP2-like transcription factors (TFs), including TARGET OF EAT 1 (TOE1), TOE2, TOE3, SCHLAFMÜTZE (SMZ), and SCHNARCHZAPFEN (SNZ) [10,11,12,13]. microRNA172, a small, non-coding RNA that can complement a region of its target genes, can post-transcriptionally repress all members of the AP2 family [14,15,16,17]. toe1 mutants have previously been shown to flower significantly early, and this effect was enhanced in toe1toe2 double-mutants [11,14]
We provide the first report of the isolation and functional characterization of AfAP2-1, an AP2-like gene in A. fasciata, a popular ornamental flowering bromeliad
Summary
The Bromeliaceae family, which consists of 3248 species in 58 genera [1,2], is one of the most morphologically diverse families with a pantropical distribution [3]. The expression of AfAP2-1 transcripts responded to plant age and ethylene treatment in A. fasciata and that the overexpression of AfAP2-1 in Columbia-0 (Col-0) background Arabidopsis (Wild Type, WT) significantly delayed flowering in both short-day (SD) and long-day (LD) conditions. These results all support the conclusion that AfAP2-1, a TF of the AP2 family, may play a pivotal role in regulating flowering time in Arabidopsis
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