Tomoya Esumi

Isolation of LEAFY and TERMINAL FLOWER 1 homologues from six fruit tree species in the subfamily Maloideae of the Rosaceae

Flowering is an essential stage of fruit production. To understand the molecular mechanisms controlling flowering in maloid fruit tree species, we isolated and analyzed genes homologous to Arabidopsis LEAFY (LFY; flower meristem identity gene) and TERMINAL FLOWER 1 (TFL1; inflorescence meristem identity gene) from six fruit tree species in the subfamily Maloideae of the Rosaceae; apple (Malus × domestica), Japanese pear (Pyrus pyrifolia), European pear (Pyrus communis), quince (Cydonia oblonga), Chinese quince (Chaenomeles sinensis), and loquat (Eriobotrya japonica). Two LFY homologues and two TFL1 homologues were cloned from all six maloid species by rapid amplification of 3′ and 5′ cDNA ends, reverse transcription-PCR, and PCR with genomic DNA. Phylogenetic analysis by the neighbor-joining method showed that the two LFY homologues and two TFL1 homologues were classified into two distinct clades. The presence of multiple copies of LFY and TFL1 homologues is discussed with reference to the polyploid origin of the subfamily Maloideae.

Identification of an FT ortholog in Japanese apricot (Prunus mume Sieb. et Zucc.)

Summary PmFT, a Prunus mume ortholog of FT (FLOWERING LOCUS T) in Arabidopsis thaliana (L.) Heynh., was isolated and characterised to elucidate the mechanism of floral bud formation in Japanese apricot (P. mume). The Japanese apricot genome contained a single locus of PmFT. PmFT consisted of a 1,473-bp open reading frame with three introns and four exons, which encoded 174 amino acid residues. The PmFT sequence showed high identity to A. thaliana FT and to FT orthologs in other plant species. Wild-type and ft-1 strains of Arabidopsis that were transformed with 35S:PmFT showed precocious flowering, indicating that PmFT has the same function as A. thaliana FT and FT orthologs in other plant species. PmFT transcripts were found in all tissues examined, with more abundant expression observed in tissues from adult trees than from seedlings.