The FLOWERING LOCUS T LIKE 2-1 gene of Chenopodium triggers precocious flowering in Arabidopsis seedlings

The FLOWERING LOCUS T (FT) gene is the essential integrator of flowering regulatory pathways in angiosperms. The paralogs of the FT gene may perform antagonistic functions, as exemplified by BvFT1, that suppresses flowering in Beta vulgaris, unlike the paralogous activator BvFT2. The roles of FT genes in other amaranths were less investigated. Here, we transformed Arabidopsis thaliana with the FLOWERING LOCUS T like (FTL) genes of Chenopodium and found, that both FTL1 and FTL2-1 accelerated flowering, despite having been the homologs of the Beta vulgaris floral promoter and suppressor, respectively. The floral promotive effect of FTL2-1 was so strong that it caused lethality when overexpressed under the 35S promoter. FTL2-1 placed in inducible cassette accelerated flowering after the induction with methoxyphenozide. The occasional expression of FTL2-1 led to precocious flowering in some primary transformants even without chemical induction. After the FTL gene duplication in Amaranthaceae, the FTL1 copy maintained the role of floral activator. The second copy FTL2 underwent subsequent duplication and functional diversification, which enabled to control the onset of flowering in amaranths to adapt to variable environments. HIGHLIGHT The FLOWERING LOCUS T like 2-1 (FTL 2-1) gene of Chenopodium acts as a strong activator of flowering in Arabidopsis, despite being a homolog of floral repressor BvFT1.