ISHS Acta Horticulturae 711: V International Symposium on Artificial Lighting in Horticulture
THE ROLE OF LIGHT AND GIBBERELLIN DEACTIVATION IN THERMOPERIODIC STEM ELONGATION - A MINI REVIEW |
| Authors: | J.A. Stavang, J. Olsen, R.. Moe |
| Keywords: | Differential temperature, plant height, GA-metabolism, temperature drop, transcriptional control |
| Abstract:
Diurnal temperature alternations affect plant stem elongation in many species. Interest in controlling plant height in greenhouse production of ornamental plants in an environmentally friendly way, has initiated extensive research on how temperature can be used to control plant morphology (Moe and Heins, 2000). In general a warm night and a cold day results in short compact plants, while a warm day and a cold night increases stem elongation and thus gives taller plants. Early reports, where hormone application was performed, indicated that gibberellins (GA) were involved in mediating thermoperiodic stem elongation. Later GA-quantification experiments confirmed this, and thermoperiodic control of GA-metabolism was suggested as an underlying mechanism of the observed growth patterns. Combined use of GA-biosynthesis inhibitors and application of different bioactive GAs, suggested that GA-deactivation was an important mechanism mediating thermoperiodic stem elongation. Further work on thermoperiodism using pea (Pisum sativum L. ‘Torsdag’) as a model system has revealed that transcriptional regulation of GA deactivation is an important mechanism controlling thermoperiodic stem elongation. Work on temperature drop, either in light or in darkness has also revealed that GA-metabolism responds differently to a temperature drop in light than in darkness. Overall these findings provide insight to the mechanisms behind the observed responses of stem elongation to diurnal temperature alternations and to temperature drop treatments. They also suggest a role for GA-deactivation in temperature acclimation of plants. | |
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