Effects of KODA on photoperiodic induction of flowering of the short-day plant Pharbitis nil cv. Violet.

Abstract

KODA (9,10-ketol-octadecadienoic acid) was initially isolated from Lemna paucicostata as a stress inducible chemical, related to flowering. In Japanese morning glory (Pharbitis nil cv. Violet), KODA is increased in the latter half of the inductive darkness showing good parallelism of the increase in mRNA level of PnFT (FLOWERING LOCUS T), the flowering hormone gene. One-hundred μM of KODA solution was applied to the seedling before and after single 12 h-dark period as a weak induction. After three weeks, KODA-treated plants bore more flower buds compared to mock-treated control plants. This increase was due to the flower bud formation at the lower node. Results of RT-PCR revealed that PnFT did not change but the timing of expression in PnAP1 (APETALA1) and PnTFL1b (TERMINAL FLOWER1b) were 2 h earlier than that in control.