Isolation of a gene, PnFL-1, expressed in Pharbitis cotyledons during floral induction

A novel gene, designated PnFL-1, was isolated from flower-induced cotyledons in a short-day plant, Pharbitis nil, using messenger RNA differential display. PnFL-1 has no similarity to genes with known functions in databases, but the deduced amino acid sequence of the gene has 58% homology with a hypothetical protein of Arabidopsis including a phosphatidic acid phosphatase 2 domain. PnFL-1 is a single-copy gene that is expressed during the inductive dark period. Expression of PnFL-1 increased gradually from the 6th to 16th h of a 16-h dark period, and expression was extinguished by a brief exposure to light at the 8th hour of the dark period (night break treatment). PnFL-1 mRNA was found in cotyledons and leaves but not in stems and roots. These results indicate that the transcription of PnFL-1 in Pharbitis may be photoperiodically regulated and associated with photoperiodic events.