The FLOWERING LOCUS T-like gene family in barley (Hordeum vulgare) Authors

The FT (FLOWERING LOCUS T) gene plays a central role in integrating flowering signals in Arabidopsis because its expression is regulated antagonistically by the photoperiod and vernalization pathways. FT belongs to a family of six genes characterised by a PEBP (phosphatidylethanolamine binding protein) domain. In rice (Oryza sativa), 19 PEBP genes were previously described, 13 of which are FT-like genes. Five FT-like genes were found in barley (Hordeum vulgare). HvFT1, HvFT2, HvFT3 and HvFT4 were highly homologous to OsFTL2 (the Hd3a QTL), OsFTL1, OsFTL10 and OsFTL12, respectively and this relationship was supported by comparative mapping. No rice equivalent was found for HvFT5. HvFT1 was highly expressed under long day (inductive) conditions at the time of the morphological switch of the shoot apex from vegetative to reproductive growth. HvFT2 and HvFT4 were expressed later in development. HvFT1 was therefore identified as the main barley FT-like gene involved in the switch to flowering. Mapping of HvFT genes suggests they provide important sources of flowering time variation in barley. HvFTI was a candidate for VRN-H3, a dominant mutation giving precocious flowering, while HvFT3 was a candidate for Ppd-H2,