scholarly journals Control of Growth in Callitriche Shoots by Growth Retardants and Gibberellic Acid

1972 ◽  
Vol 25 (3) ◽  
pp. 637
Author(s):  
CH Wong ◽  
A JMccomb
Keyword(s):  
Gibberellic Acid ◽  
Water Surface ◽  
Higher Plants ◽  
Gibberellin Biosynthesis ◽  
Growth Retardants

Shoots of the aquatic, Callitriche, form floating rosettes of leaves, the internodes of which elongate if the shoot is submerged, or treated at the water surface with gibberellic acid (McComb 1965; Wong and McComb 1967). It may therefore be tentatively proposed that submerged shoots synthesize more gibberellin than do floating shoots. To obtain further information concerning this hypothesis, investiga-tions have been carried out with the growth retardants Amo1618 and CCC, com-pounds which characteristically bring about dwarfing in higher plants, an effect reversed by gibberellin (e.g. McComb and McComb 1970), and which have been shown to inhibit gibberellin biosynthesis in certain systems (e.g. Baldev, Lang, and Agatep 1965; Dennis, Upper, and West 1965; Zeevaart 1966).

scholarly journals The Current Status of Research on Gibberellin Biosynthesis

2020 ◽  
Vol 61 (11) ◽  
pp. 1832-1849 ◽  
Author(s):  
Peter Hedden
Keyword(s):  
Gibberellic Acid ◽  
Vascular Plants ◽  
Molecular Mechanisms ◽  
Bacterial Species ◽  
Current Status ◽  
Fusarium Fujikuroi ◽  
Environmental Cues ◽  
Gibberellin Biosynthesis ◽  
Gibberellin Metabolism ◽  
Recent Advances

Abstract Gibberellins are produced by all vascular plants and several fungal and bacterial species that associate with plants as pathogens or symbionts. In the 60 years since the first experiments on the biosynthesis of gibberellic acid in the fungus Fusarium fujikuroi, research on gibberellin biosynthesis has advanced to provide detailed information on the pathways, biosynthetic enzymes and their genes in all three kingdoms, in which the production of the hormones evolved independently. Gibberellins function as hormones in plants, affecting growth and differentiation in organs in which their concentration is very tightly regulated. Current research in plants is focused particularly on the regulation of gibberellin biosynthesis and inactivation by developmental and environmental cues, and there is now considerable information on the molecular mechanisms involved in these processes. There have also been recent advances in understanding gibberellin transport and distribution and their relevance to plant development. This review describes our current understanding of gibberellin metabolism and its regulation, highlighting the more recent advances in this field.

scholarly journals Wheat Germination Is Dependent on Plant Target of Rapamycin Signaling

2020 ◽  
Vol 8 ◽  
Author(s):  
Bauyrzhan Smailov ◽  
Sanzhar Alybayev ◽  
Izat Smekenov ◽  
Aibek Mursalimov ◽  
Murat Saparbaev ◽  
...  
Keyword(s):  
Gene Expression ◽  
De Novo ◽  
Higher Plants ◽  
Target Of Rapamycin ◽  
Central Component ◽  
Gibberellin Biosynthesis ◽  
Aleurone Layer ◽  
Dependent Manner ◽  
Wheat Embryo ◽  
Wheat Germination

Germination is a process of seed sprouting that facilitates embryo growth. The breakdown of reserved starch in the endosperm into simple sugars is essential for seed germination and subsequent seedling growth. At the early stage of germination, gibberellic acid (GA) activates transcription factor GAMYB to promote de novo synthesis of isoforms of α-amylase in the aleurone layer and scutellar epithelium of the embryo. Here, we demonstrate that wheat germination is regulated by plant target of rapamycin (TOR) signaling. TOR is a central component of the essential-nutrient–dependent pathway controlling cell growth in all eukaryotes. It is known that rapamycin, a highly specific allosteric inhibitor of TOR, is effective in yeast and animal cells but ineffective in most of higher plants likely owing to structural differences in ubiquitous rapamycin receptor FKBP12. The action of rapamycin on wheat growth has not been studied. Our data show that rapamycin inhibits germination of wheat seeds and of their isolated embryos in a dose-dependent manner. The involvement of Triticum aestivum TOR (TaTOR) in wheat germination was consistent with the suppression of wheat embryo growth by specific inhibitors of the TOR kinase: pp242 or torin1. Rapamycin or torin1 interfered with GA function in germination because of a potent inhibitory effect on α-amylase and GAMYB gene expression. The TOR inhibitors selectively targeted the GA-dependent gene expression, whereas expression of the abscisic acid-dependent ABI5 gene was not affected by either rapamycin or torin1. To determine whether the TaTOR kinase activation takes place during wheat germination, we examined phosphorylation of a ribosomal protein, T. aestivum S6 kinase 1 (TaS6K1; a substrate of TOR). The phosphorylation of serine 467 (S467) in a hydrophobic motif on TaS6K1 was induced in a process of germination triggered by GA. Moreover, the germination-induced phosphorylation of TaS6K1 on S467 was dependent on TaTOR and was inhibited by rapamycin or torin1. Besides, a gibberellin biosynthesis inhibitor (paclobutrazol; PBZ) blocked not only α-amylase gene expression but also TaS6K1 phosphorylation in wheat embryos. Thus, a hormonal action of GA turns on the synthesis of α-amylase in wheat germination via activation of the TaTOR–S6K1 signaling pathway.

scholarly journals Effectiveness of Plant Growth Regulators under Photoselective Greenhouse Covers

2000 ◽  
Vol 125 (6) ◽  
pp. 673-678 ◽  
Author(s):  
Anuradha Tatineni ◽  
Nihal C. Rajapakse ◽  
R. Thomas Fernandez ◽  
James R. Rieck
Keyword(s):  
Plant Height ◽  
Control Mechanism ◽  
Chrysanthemum Morifolium ◽  
Photon Flux ◽  
Gibberellin Biosynthesis ◽  
Growth Retardants ◽  
Water Control ◽  
Height Control ◽  
Height Reduction ◽  
Height Increase

Responses to selected chemical growth retardants (daminozide, paclobutrazol, and prohexadione-Ca) and GA1 and GA3 under photoselective greenhouse covers with various phytochrome photoequilibrium estimates (φe) were evaluated using `Bright Golden Anne' chrysanthemum [Dendranthema ×grandiflora Kitam. (syn. Chrysanthemum morifolium Ramat.)] as the model plant to better understand the height control mechanism by far red (FR) light depleted environments. Plant height linearly decreased as φe increased from 0.72 to 0.83. The rate of height decrease of daminozide treated plants was less than that of water (control) or GA3-treated plants. The rate of height reduction was not different between control and GA3-treated plants among chambers with various φe. Both paclobutrazol and prohexadione-Ca reduced plant height regardless of φe, but the height reduction by paclobutrazol was more than that by prohexadioneCa. The combination of paclobutrazol and prohexadione-Ca reduced plant height more than either alone. GA1 reversed the height reduction caused by paclobutrazol and prohexadione-Ca regardless of φe, but the height increase by GA1 was more when it was applied with prohexadione-Ca than when applied alone. Results show that photoselective covers with high φe were effective in controlling height of chrysanthemums without chemical growth retardants. The linear relationship between plant height and φe suggests that effectiveness of photoselective covers increased as φe increased. The photosynthetic photon flux (PPF) transmission of photoselective covers decreased as the φe increased because of the increasing dye concentration. Identifying photoselective covers that effectively filter out FR light from sunlight and reduce plant height while minimizing the PPF reduction is critical for commercial success of photoselective covers. Gibberellins are, at least partially, involved in height control by photoselective covers. Photoselective greenhouse covers did not reduce responsiveness to gibberellins, and it appears that the mechanism may be to suppress gibberellin biosynthesis. Results also suggest that increased metabolism of GA1 to GA8 was not the mechanism of height control by photoselective covers. Chemical names used: butanedioic acid mono (2,2-dimethylhydrazide) [daminozide]; (±)-(R*,R*)-b-((4-chlorophenyl)methyl)-a-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol [paclobutrazol]; 3,5-dioxo-4-(1-oxopropyl)cyclohexanecarboxylic acid [prohexadione-Ca]; gibberellic acid [GA].

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