Functional characterization of FT and MFT ortholog genes in orchid (Dendrobium nobile Lindl) that regulate the vegetative to reproductive transition in Arabidopsis

摘要

Genes belonging to the phosphoethanolamine binding protein (PEBP) superfamily play important roles in controlling the switch between vegetative and reproductive growth in higher plants. Here we reported the isolation of two genes from the PEBP superfamily in Dendrobium nobile Lindl homologous to FLOWERING LOCUS T (FT) and MOTHER OF FT (MFT). These two genes, designated as DnFT and DnMFT, were predominantly expressed in the auxiliary buds and leaves of the plant. In auxiliary buds, DnFT was expressed at a higher level in young buds than in mature buds, while mature leaves expressed more DnFT than young ones. Low temperature treatment led to an increased expression of DnFT in leaves, but a decreased expression in buds. In contrast, the expression of DnMFT increased in buds and decreased in leaves during flower bud development and was not influenced by low temperature treatment. Ectopic expression of DnFT in Arabidopsis plants showed an early-flowering phenotype and inflorescence indeterminacy loss. Over-expression of DnMFT in Arabidopsis led to slightly late-flowering. Our results revealed that DnFT functions as a floral inducer in D. nobile Lindl by regulating flower transition in a similar way to its ortholog in Arabidopsis. Early flowering, induced by a low temperature treatment, was probably due to the activation of DnFT transcription in D. nobile Lindl.