Occurrence of Gibberellins in Vascular Plants, Fungi, and Bacteria

MacMillan, Jake

doi:10.1007/s003440010038

Cited by 306 publications

(166 citation statements)

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“…Occurrence, biosynthesis and biological activity GAs have been detected in a range of terrestrial vascular plants, including ferns and gymnosperms, and are also present in some fungi and bacteria (MacMillan 2002). Compared with auxin, our understanding of GA synthesis is markedly superior.…”

Section: Gibberellinsmentioning

confidence: 99%

Evolution of growth-promoting plant hormones

Ross

Reid

2010

Functional Plant Biol.

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Abstract. The plant growth hormones auxin, gibberellins (GAs) and brassinosteroids (BRs) are major determinants of plant growth and development. Recently, key signalling components for these hormones have been identified in vascular plants and, at least for the GAs and BRs, biosynthetic pathways have been clarified. The genome sequencing of a range of species, including a few non-flowering plants, has allowed insight into the evolution of the hormone systems. It appears that the moss Physcomitrella patens can respond to auxin and contains key elements of the auxin signalling pathway, although there is some doubt as to whether it shows a fully developed rapid auxin response. On the other hand, P. patens does not show a GA response, even though it contains genes for components of GA signalling. The GA response system appears to be more advanced in the lycophyte Selaginella moellendorffii than in P. patens. Signalling systems for BRs probably arose after the evolutionary divergence of the mosses and vascular plants, although detailed information is limited. Certainly, the processes affected by the growth hormones (e.g. GAs) can differ in the different plant groups, and there is evidence that with the evolution of the angiosperms, the hormone systems have become more complex at the gene level. The intermediate nature of mosses in terms of overall hormone biology allows us to speculate about the possible relationship between the evolution of plant growth hormones and the evolution of terrestrial vascular plants in general.

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Section: Gibberellinsmentioning

confidence: 99%

Evolution of growth-promoting plant hormones

Ross

Reid

2010

Functional Plant Biol.

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“…Gibberellin (GA), another growth regulator, promotes plant growth in higher plants, but is also produced by fungi and bacteria (MacMillan 2001). It is presumed that GAs in fungi and bacteria are secondary metabolites that act as signaling factors to establish the interaction with host plants.…”

Section: Introductionmentioning

confidence: 99%

Plant growth hormones suppress the development of Harpophora maydis, the cause of late wilt in maize

Degani

Drori

Goldblat

2014

Physiol Mol Biol Plants

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Late wilt, a severe vascular disease of maize caused by the fungus Harpophora maydis, is characterized by rapid wilting of maize plants before tasseling and until shortly before maturity. The pathogen is currently controlled by resistant maize cultivars, but the disease is constantly spreading to new areas. The plant's late phenological stage at which the disease appears suggests that plant hormones may be involved in the pathogenesis. This work revealed that plant growth hormones, auxin (Indole-3-acetic acid) and cytokinin (kinetin), suppress H. maydis in culture media and in a detached root assay. Kinetin, and even more auxin, caused significant suppression of fungus spore germination. Gibberellic acid did not alter colony growth rate but had a signal suppressive effect on the pathogens' spore germination. In comparison, ethylene and jasmonic acid, plant senescing and defense response regulators, had minor effects on colony growth and spore germination rate. Their associate hormone, salicylic acid, had a moderate suppressive effect on spore germination and colony growth rate, and a strong influence when combined with auxin. Despite the anti-fungal auxin success in vitro, field experiments with dimethylamine salt of 2,4-dichlorophenoxyacetic acid (that mimics the influence of auxin) failed to suppress the late wilt. The lines of evidence presented here reveal the suppressive influence of the three growth hormones studied on fungal development and are important to encourage further and more in-depth examinations of this intriguing hormonal complex regulatory and its role in the maize-H. maydis interactions.

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“…However, based on the prevalence of 2b-hydroxylated GAs in many plant species (MacMillan, 2002), the most widespread mechanism for GA inactivation seems to be via 2-oxidation, in which the diterpene backbone is hydroxylated at C-2b and, in some cases, further oxidized to a ketone (Sponsel and Macmillan, 1978;Thomas et al, 1999), which undergoes nonenzymatic rearrangement to form a so-called GA catabolite. Biochemical characterization of the enzymes responsible for 2b-hydroxylation showed that, like the GA 20-oxidases and GA 3-oxidases, they belong to the soluble 2-oxoglutarate-dependent dioxygenase class (Griggs et al, 1991).…”

Section: Introductionmentioning

confidence: 99%

Genetic Analysis Reveals That C19-GA 2-Oxidation Is a Major Gibberellin Inactivation Pathway inArabidopsis

et al. 2008

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Bioactive hormone concentrations are regulated both at the level of hormone synthesis and through controlled inactivation. Based on the ubiquitous presence of 2β-hydroxylated gibberellins (GAs), a major inactivating pathway for the plant hormone GA seems to be via GA 2-oxidation. In this study, we used various approaches to determine the role of C19-GA 2-oxidation in regulating GA concentration and GA-responsive plant growth and development. We show that Arabidopsis thaliana has five C19-GA 2-oxidases, transcripts for one or more of which are present in all organs and at all stages of development examined. Expression of four of the five genes is subject to feed-forward regulation. By knocking out all five Arabidopsis C19-GA 2-oxidases, we show that C19-GA 2-oxidation limits bioactive GA content and regulates plant development at various stages during the plant life cycle: C19-GA 2-oxidases prevent seed germination in the absence of light and cold stimuli, delay the vegetative and floral phase transitions, limit the number of flowers produced per inflorescence, and suppress elongation of the pistil prior to fertilization. Under GA-limited conditions, further roles are revealed, such as limiting elongation of the main stem and side shoots. We conclude that C19-GA 2-oxidation is a major GA inactivation pathway regulating development in Arabidopsis.

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Occurrence of Gibberellins in Vascular Plants, Fungi, and Bacteria

Abstract: The occurrence of GA1 to GA126 in vascular plants, fungi, and bacteria is listed. The data are discussed with reference to criteria for identification and to the frequency of occurrence of GAs in vascular plants.

Cited by 306 publications

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Evolution of growth-promoting plant hormones

Evolution of growth-promoting plant hormones

Plant growth hormones suppress the development of Harpophora maydis, the cause of late wilt in maize

Genetic Analysis Reveals That C19-GA 2-Oxidation Is a Major Gibberellin Inactivation Pathway inArabidopsis

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