The effects of daylength on protein synthesis and flowering in Doritis pulcherrima

Abstract Mature doritis plants (Doritis pulcherrima Lindley, cv. S94-3345) were cultured in plastic pots with 9 h (short-day, SD) and 16 h (long-day, LD) photoperiods, respectively. The main 9 h light period was under field conditions (30 °C day/20 °C night on average). The supplemental 7 h light conditions for the LD were conducted in chambers with 14 μmol m−2 s−1 photosynthetic photon flux. When transferred to SD for 30 days, flower spikes about 2.0–3.0 cm in length were initiated. When plants were transferred to SD for 45 days, spikes grew to 7.0–10.0 cm in length. In contrast, only 10% of the plants produced flowering shoots under LD conditions. Unique 21 and 103 kDa proteins were evident in one-dimensional electrophoresis of proteins from mature leaves under SD conditions. 2D gel electrophoresis confirmed that clear polypeptide spots with a molecular mass of 21 kDa at an isoelectric point of 5.2 and 103 kDa at an isoelectric point of 5.6 accumulated in the leaves when the flowering shoots reached 7.0–10.0 cm (4–5 flower primordia apparent). Possibly, the 21 and 103 kDa proteins play a role during flowering shoot formation in doritis. Polypeptide sequencing of P21 suggested a possible relationship to the cell division-like protein in Arabidopsis thaliana. It is clear that doritis is a facultative SD plant, and photoperiodic induction of its flowering is closely associated with protein synthesis changes in its leaves.