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 x 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.