Gibberellin structure and florigenic activity in Lolium temulentum, a long-day plant

Structural requirements for florigenic activity among gibberellins (GAs) and GA derivatives, including several new ones, applied once to leaves of Lolium temulentum, were examined. The compounds were applied to plants kept either in non-inductive short days (SD) or exposed to one inductive long day...

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Bibliographic Details
Published in:Planta 1990-08, Vol.182 (1), p.97-106
Main Authors: Evans, L.T. (CSIRO, Canberra (Australia). Div. of Plant Industry), King, R.W, Chu, A, Mander, L.N, Pharis, R.P
Format: Article
Language:English
Subjects:
ACIDO GIBERELICO
Bluetenentwicklung
Blueteninduktion
CRECIMIENTO
CROISSANCE
Dose response relationship
Esters
FLORACION INDUCIDA
FLORAISON INDUITE
Flowering
FOTOPERIODISMO
Gibberellin
GIBBERELLINE
Gibberellins
GROWTH
Hydroxyls
INDUCED FLOWERING
Inflorescences
LOLIUM
Metabolism
Photoperiod
Photoperiode
PHOTOPERIODICITE
PHOTOPERIODICITY
Plants
Sprosswachstum
Stem elongation
STEMS
TALLO
TIGE
Wachstumsregulator
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Summary:Structural requirements for florigenic activity among gibberellins (GAs) and GA derivatives, including several new ones, applied once to leaves of Lolium temulentum, were examined. The compounds were applied to plants kept either in non-inductive short days (SD) or exposed to one inductive long day (LD). Inflorescence initiation and stem-elongation responses were assessed three weeks later. Among the GAs used, the range in effective dose for inflorescence initiation was more than 1000-fold, but substantially less for stem elongation. Some GAs promoted both stem elongation and inflorescence initiation, some promoted one without the other, and some affected neither. The structural features enhancing florigenic activity were often different from those enhancing stem elongation. Except in the case of 2,2-dimethyl GA4, a double bond in the A ring at either C-1,2 or C-2,3 was essential for high florigenic activity, though not for stem elongation. A free carboxy group was needed for both. Inflorescence initiation in Lolium was enhanced by hydroxylation at C-12, -13 and -15, whereas hydroxylation at C-3 reduced the effect on inflorescence initiation but increased that on stem elongation. A 12β-hydroxyl was more effective than the α epimer for inflorescence initiation whereas the reverse was true for stem elongation. Although such differential effectiveness of GAs for inflorescence initiation and for stem elongation could reflect differences in uptake, transport or metabolism, we suggest that it is indicative of specific structural requirements for inflorescence initiation.
ISSN:0032-0935
1432-2048
DOI:10.1007/BF00239990