Objective Expressions and functions of Flowering Locus T (FT), the genes widely involved in plant growth, flowering regulation, root development, and seed germination, in Chinese narcissus were studied.
Method Four FTs were identified from the transcriptome data on Narcissus tazetta var. chinensis Roem by bioinformatics analysis. Expressions of the genes in various tissues and flower buds at differentiation stages were determined by fluorescence quantitative PCR and further confirmed by overexpressing it in Arabidopsis thaliana.
Result The 4 homologous FTs, i.e., NtFT1, NtFT2, NtFT3, and NtFT4, were cloned using RT-PCR. All of them, except NtFT3, had conserved motifs. Phylogenetically; NtFT1 belonged to the FT-like I branch, while NtFT2, NtFT3, and NtFT4, to the FT-like II branch. In tissues, organs, and flower buds at differentiation stages, they expressed differently. The highest expressions of NtFT1 and NtFT3 were in the flowers, those of NtFT2 in the leaves, and NtFT4 in the scales. At different flower bud differentiation stages, the expressions differed significantly as well, as NtFT1 decreased followed as an increase during differentiation, but NtFT2 changed little throughout. The expressions of NtFT3 and NtFT4 were relatively low in the entire flower bud differentiation period. The ectopic transformation of A. thaliana showed the overexpressed NtFT1 and NtFT2 led to early flowering in comparison to the wild type. But no effect was associated with NtFT3, but delayed flowering was found on the transgenic NtFT4 Arabidopsis plants. In addition, the expressions of SOC1, LFY, and AP1 in the Arabidopsis plants rose with NtFT1 overexpression.
Conclusion There were multiple FTs in Chinese narcissus that differed in regulating the flowering—NtFT1 promoted, while NtFT4 inhibited, the process.
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