The Effect of Gibberellins on Flowering in Roses

Abstract

The gibberellins A(1), A(3), A(5), A(8), A(19), A(20), and A(29) were identified in vegetative shoot tips of Rosa canina by comparing their mass spectra and Kovats retention indices with those of standards. Most wild roses have a short flowering season of 2-4 weeks in spring, whereas most modern cultivars flower recurrently. 'Félicité et Perpétue' is a short-season hybrid from a cross between a wild rose and a recurrent-flowering rose, whereas its sport, 'Little White Pet,' flowers recurrently. The concentrations of gibberellins (GAs) were measured in shoot apices of both cultivars. In March (before floral initiation in spring) the concentrations of GA(1) and GA(3) were respectively threefold and twofold higher in 'Félicité et Perpétue' than in 'Little White Pet.' In April (after floral initiation) the concentrations of both gibberellins were substantially greater than in March, and concentrations of GA(1) and GA(3) were, respectively, 17-fold and 12-fold greater in 'Félicité et Perpétue' than in 'Little White Pet.' It is postulated that, in 'Félicité et Perpétue,' floral initiation occurs when concentrations of GAs are low and is inhibited when concentrations of GAs are high, whereas in 'Little White Pet' concentrations of GAs remain at permissive levels throughout the growing season. Applications of GA(1) and GA(3) to axillary shoots in March inhibited floral development in 'Félicité et Perpétue' but not in 'Little White Pet.' This suggests that the combined concentration of exogenous and endogenous gibberellins might have been raised to inhibitory levels in the former but not in the latter cultivar.

Comparative transcriptome analysis of the floral transition in Rosa chinensis ‘Old Blush’ and R. odorata var. gigantea

“…GA plays an activating role in regulating the floral transition in A . thaliana , but GAs are maintained at low levels during the floral transition process in both CF and seasonal roses (OF), and increase after flowering 16 . Spraying application of GA 3 could block the floral transition in OF roses, but not in CF roses.…”

Methylation of Gibberellins by Arabidopsis GAMT1 and GAMT2

“…A developing solution of chloroform and methanol in a ratio of 9:1 v/v was used as described by Roberts et al (1999). The retention time of obtained radioactive products was compared with nonradioactive standards (prepared by L. Mander) or methylated GA standards with (trimethylsilyl)diazomethane (Sigma-Aldrich).…”

“…The retention time of obtained radioactive products was compared with nonradioactive standards (prepared by L. Mander) or methylated GA standards with (trimethylsilyl)diazomethane (Sigma-Aldrich). For visualization of the nonradioactive GAs and their methylesters, the TLC plate was sprayed with sulfuric acid:ethanol (1:20 [v/v]) and then heated at 1108C for 10 min (Roberts et al, 1999).…”

Molecular Cloning and Expression Analysis of 13 MADS-Box Genes in Betula platyphylla

“…While the role of GAs in flowering has been established for a limited number of species, GA is clearly not a universal flowering stimulus. In some species, such as the LD grass Lolium temulentum, there is convincing evidence that GA acts as a mobile signal to transmit the photoperiodic flowering stimulus, while in others it appears to have little influence on flower initiation and in many perennials it inhibits flowering (King et al 2006;Boss and Thomas 2002;Roberts et al 1999). In this study, all of the BpMADS genes were shown to be responsive to exogenous GA treatment, demonstrating that GA-dependent molecular genetic pathways regulate these MADSs.…”