Abstract
Photoperiods regulate expression of various genes involved in circadian rhythm, photosynthesis and flowering. In Pharbitis nil, the exposure to a single dark period of 16 h can induce flowering. In order to identify novel genes involved in flowering induction, we have isolated two genes induced by a 14 h dark treatment from P. nil using a cDNA subtraction. These genes are highly homologous to ubiquitin 1,2 and unknown gene in Arabidopsis. The expression of both genes in cotyledons was induced by dark treatment of 12-16 h. Accumulation of these transcripts was reduced by a brief exposure to white light at the 8 h of the dark period (night break treatment) or by exposure to far-red light at the end of the light period (end-of-day far-red treatment). Possible involvement of these genes in flowering induction will be discussed.
