The Bromeliaceae family, which is distributed pantropically, is one of the most morphologically diverse families. Except for the edible pineapple (Ananas comosus), the vast majority of bromeliads cultivated worldwide are appreciated mainly for their ornamental value. As subtropical and tropical flowering plants, these bromeliads, among with Aechmea fasciata, have significant economic importance. However, the molecular mechanism of flowering in bromeliads remains unrevealed. In this study, an APETALA2 (AP2) homologue, AfAP2-2, which belongs to the AP2/ethylene response element binding protein (AP2/EREBP) transcription factor superfamily, was identified in A. fasciata. AfAP2-2 contains two conserved AP2 domains and is a nuclear-localized transactivator. The expression level of AfAP2-2 was predominantly higher in vegetative organs of the reproductive phase than in those of the vegetative phase. Ectopic expression of AfAP2-2 in Arabidopsis specifically delayed flowering in short-day (SD) conditions. Furthermore, the size and weight of seeds of AfAP2-2-overexpressing Arabidopsis plants were significantly reduced compared to those of the wild type (WT). Our findings suggest that AfAP2-2 might be a negative regulator of flowering and seed size and weight. These results may help facilitate the molecular breeding of bromeliads.
Keywords: APETALA2; Aechmea fasciata; Bromeliad; Flowering; Seed size; Transcriptional activator.
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