Abstract
We investigated the expression of Japanese pear (Pyrus pyrifolia) and quince (Cydonia oblonga) homologs of Arabidopsis thaliana flowering-related genes LEAFY (LFY) and TERMINAL FLOWER 1 (TFL1) in dissected floral tissues. Japanese pear and quince belong to the subfamily Maloideae (Rosaceae), which is an ancient polyploid; thus, the genome of each plant contains at least two different homologs of LFY and TFL1. We examined the expression of each homolog separately using gene-specific reverse transcription-polymerase chain reaction (RT-PCR). Under the experimental conditions used in this study, there was no difference in the expression pattern of LFY homologs, regardless of the species and homolog type. In contrast, TFL1 homologs were differentially expressed in Japanese pear and quince. In Japanese pear, PpTFL1-1 and PpTFL1-2 were expressed in the apical meristem prior to floral differentiation; however, during floral differentiation, PpTFL1-2 expression disappeared and PpTFL1-1 alone continued to be expressed in the developing inflorescence. In quince, CoTFL1-1 was the only TFL1 homolog detected prior to floral differentiation. Upon floral differentiation, both CoTFL1-1 and CoTFL1-2 were expressed mainly in the domed apical meristem. These expressions decreased to an undetectable level once the apical meristem had transformed into a single flower meristem. Thus, Japanese pear and quince TFL1 homologs are supposed to be involved in the formation of domed apical meristems during early reproductive development. Our results imply the importance of PpTFL1-1 in morphological development of Japanese pear inflorescence.
