The FLOWERING LOCUS T/TERMINAL FLOWER 1 family in Lombardy poplar

Genes in the FLOWERING LOCUS T (FT) and TERMINAL FLOWER 1 (TFL1)family have been shown to be important in the control of theswitch between vegetative and reproductive growth in severalplant species. We isolated nine members of the FT/TFL1 familyfrom Lombardy poplar (Populus nigra var. italica Koehne). Sequenceanalysis of the members of the FT/TFL1 family revealed considerablehomology within their coding regions both among family membersand to the members of the same family in Arabidopsis, tomatoand grapevine. Moreover, members of this family in all fourspecies examined display a common exon–intron organization.Phylogenetic analysis revealed that the genes fall into fourdifferent clades: two into the TFL1 clade; five into the FTclade; and one each into the MOTHER OF FT AND TFL1 and BROTHEROF FT AND TFL1 clades. One gene in the TFL1 clade, PnTFL1, isexpressed in vegetative meristems, and transgenic Arabidopsisthat ectopically expressed PnTFL1 had a late-flowering phenotype.The expression patterns of two genes in the FT clade, PnFT1and PnFT2, suggested a role for them in the promotion of flowering,and transgenic Arabidopsis that ectopically expressed eitherPnFT1 or PnFT2 had an early-flowering phenotype.