Articles
THE ROLE OF GIBBERELLINS IN THE THERMO- AND PHOTOCONTROL OF STEM ELONGATION IN FUCHSIA
Article number
435_8
Pages
93 – 104
Language
Abstract
Stem elongation in Fuchsia x hybrida was influenced by cultivation at different day and night temperature or in different light qualities.
Internode elongation of plants grown at a day (25°C) night (15°C) temperature difference (DIF+10) in white light was almost twofold of that of plants grown at the opposite temperature regime (DIF-10). Orange light resulted in a threefold stimulation of internode elongation as compared to white light DIF-10. Surprisingly, internode elongation in orange light was similar for plants grown at DIF-10 and DIF+10. In white light an increase in irradiance level did not affect shoot length at either DIF treatment.
Flower development was accelerated at DIF-10 as compared to DIF+10 in both white and orange light.
To examine whether DIF- and light quality-induced changes in shoot elongation were related to changes in gibberellin metabolism or plant sensitivity to gibberellins, the stem elongation responses of paclobutrazol-treated plants to exogenously applied GAs were determined.
In the absence of applied gibberellins, paclobutrazol (> 0.32 μmol plant-1) strongly retarded shoot elongation.
This inhibition was nullified by the application of GA1, GA4, GA9, GA15, GA19, GA20, GA24 and GA44 of about 10 to 32 nmol plant-1, but not by GA12 which only slightly increased stem elongation at an amount of 100 nmol plant-1. The results are discussed in relation to possible effects of DIF and light quality on endogenous gibberellin levels and gibberellin sensitivity of fuchsia, and their effect on stem elongation.
Internode elongation of plants grown at a day (25°C) night (15°C) temperature difference (DIF+10) in white light was almost twofold of that of plants grown at the opposite temperature regime (DIF-10). Orange light resulted in a threefold stimulation of internode elongation as compared to white light DIF-10. Surprisingly, internode elongation in orange light was similar for plants grown at DIF-10 and DIF+10. In white light an increase in irradiance level did not affect shoot length at either DIF treatment.
Flower development was accelerated at DIF-10 as compared to DIF+10 in both white and orange light.
To examine whether DIF- and light quality-induced changes in shoot elongation were related to changes in gibberellin metabolism or plant sensitivity to gibberellins, the stem elongation responses of paclobutrazol-treated plants to exogenously applied GAs were determined.
In the absence of applied gibberellins, paclobutrazol (> 0.32 μmol plant-1) strongly retarded shoot elongation.
This inhibition was nullified by the application of GA1, GA4, GA9, GA15, GA19, GA20, GA24 and GA44 of about 10 to 32 nmol plant-1, but not by GA12 which only slightly increased stem elongation at an amount of 100 nmol plant-1. The results are discussed in relation to possible effects of DIF and light quality on endogenous gibberellin levels and gibberellin sensitivity of fuchsia, and their effect on stem elongation.
Authors
Frank M. Maas, J. Hattum
Keywords
blue-light receptor, DIF, Fuchsia x hybrida, fuchsia, light quality, paclobutrazol, photomorphogenesis, phytochrome, temperature, thermomorphogenesis
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