Identification and Seasonal Variation of Endogenous Cytokinins in <i>Ecklonia maxima </i>(Osbeck) Papenf.

Featonby-Smith, B.C.; Staden, J. Van

doi:10.1515/botm.1984.27.11.527

Cited by 59 publications

(21 citation statements)

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“…It may be expected that if plant hormones are important in regulating growth and developmental processes in seaweeds, they will show some seasonal fluctuations in their composition and concentrations. Studies in the 1980s demonstrated there was a seasonal variation in cytokinin-like activity in some brown seaweeds, with an increase in cytokinin-like activity (cytokinin free bases and riboside-like activity) in samples collected during periods of active growth, while there was an increase in cytokinin-O-glucoside-like activity in samples collected during periods of slower growth in Ecklonia maxima (Featonby-Smith & van Staden, 1984), Sargassum heterophyllum (Mooney & van Staden, 1984) and Macrocystis pyrifera (de Nys et al, 1990). Cytokinin-like activity also increased in the vegetative laterals of Sargassum heterophyllum to coincide with gamete release and the onset of regenerative growth, while activity in the reproductive laterals increased to coincide with gamete release and receptacle initiation (Mooney & van Staden, 1984).…”

Section: Introductionmentioning

confidence: 99%

Endogenous cytokinins, auxins and abscisic acid inUlva fasciata(Chlorophyta) andDictyota humifusa(Phaeophyta): towards understanding their biosynthesis and homoeostasis

Stirk

Novák

Hradecká

et al. 2009

European Journal of Phycology

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Hormones are present in seaweeds, but little is known about their biosynthesis and regulation. The aim of this study was to investigate variation in concentration and composition of endogenous cytokinins, auxins and abscisic acid in two seaweeds collected over a 1 year period to gain a more complete picture of the types of hormones present during a range of environmental and developmental conditions. Ulva fasciata (Ulvales, Chlorophyta) and Dictyota humifusa (Dictyotales, Phaeophyta) were collected bimonthly from the inter-tidal zone at Rocky Bay, South Africa. Ethanol extracts of the samples containing a mixture of internal standards were purified using a combined DEAE-Sephadex-octadecylsilica column, followed by immuno-affinity chromatography and analysed by high-performance liquid chromatography -mass spectrometry to quantify different cytokinins, auxins and abscisic acid. cis-Zeatin, isopentenyladenine and their ribotide and riboside conjugates were the main cytokinins present in both U. fasciata and D. humifusa with low concentrations of trans-zeatin, dihydrozeatin and aromatic cytokinins. Very low concentrations of O-glucosides and riboside-O-glucosides and no N-glucosides were detected in any of the samples. Based on the cytokinins detected, we propose that as in higher plants, the ribotides are also the first intermediates formed during de novo biosynthesis in seaweeds and are subsequently converted to free-bases and ribosides. The only indole compounds detected in both species were free indole-3-acetic acid and indole-3-acetamide (IAM), suggesting that IAM is the intermediate in auxin biosynthesis. Endogenous abscisic acid was detected in most samples with levels in U. fasciata generally being higher than those measured in D. humifusa.

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Section: Introductionmentioning

confidence: 99%

Endogenous cytokinins, auxins and abscisic acid inUlva fasciata(Chlorophyta) andDictyota humifusa(Phaeophyta): towards understanding their biosynthesis and homoeostasis

Stirk

Novák

Hradecká

et al. 2009

European Journal of Phycology

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“…SWC also enhanced the growth of potato plantlets in vitro (Crouch & Van Staden, 1991). The active components were suggested to be cytokinins (Featonby-Smith & Van Staden, 1984) and auxins . The effect of SWC on plant growth often depends on the concentration used and on the mode of application , 1993Atzmon & Van Staden, 1994;Van Staden et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

The effect of a seaweed concentrate on the in vitro growth and acclimatization of potato plantlets

1999

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SummaryThe seaweed concentrate 'Kelpak' is used commercially in the greenhouse and field to improve plant quality. 'Kelpak' was added to the in vitro culture medium of potato cv. 'BPI' and also applied as a leaf/soil drench immediately after transplanting. The addition of 0.25% seaweed concentrate to the medium improved plantlet quality and led to better establishment in the greenhouse. No beneficial effect of seaweed concentrate in the tissue culture medium was observed if a second cutting was part of the micropropagation process. Additional application of 0.5% seaweed concentrate in the greenhouse to plantlet cuttings derived from tissue culture was not beneficial.

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“…The components of various seaweed products that are responsible for the beneficial effects are unknown, but compounds with cytokinin-like properties are believed to be of major importance. Cytokinins have been isolated from several products and characterised (Featonby-Smith & van Staden, 1984;Tay et al, 1985Tay et al, , 1987Sanderson & Jameson, 1986). However, different bioassays that have been used to analyse the content of cytokinins in seaweed extracts have led to widely different results.…”

Section: Introductionmentioning

confidence: 99%

Significance of betaines in the increased chlorophyll content of plants treated with seaweed extract

et al. 1993

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Seaweed extract, prepared by alkaline extraction of Ascophyllum nodosum (L.) Le Jol., applied either to the soil or to the foliage of tomato plants, produced leaves with higher chlorophyll levels than those of control plants. The effects on leaf chlorophyll content were investigated using a cucumber bioassay procedure devised for cytokinins. The seaweed extract was shown to increase the chlorophyll levels of the cucumber cotyledons, but 'peaks' of activity were obtained when widely different concentrations were used. The possibility that these effects were the result of betaines present in the extract was considered. Glycinebetaine, y-aminobutyric acid betaine and 6-aminovaleric acid betaine all produced significantly enhanced chlorophyll concentrations in the cotyledons. 'Peaks' of activity were observed for each betaine: for glycinebetaine at 10-6 and between 10-4 and 10' mg 1-', for y-aminobutyric acid betaine at 10-6, between 10-4 and 10 -1, and 10' mg -, and for 6-aininovaleric acid betaine between 10-5 and 10 mg 1-1. It was concluded that the effects of enhancing chlorophyll levels produced by the seaweed extract were due, at least in part, to betaines.

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Identification and Seasonal Variation of Endogenous Cytokinins in Ecklonia maxima (Osbeck) Papenf.

Cited by 59 publications

References 0 publications

Endogenous cytokinins, auxins and abscisic acid inUlva fasciata(Chlorophyta) andDictyota humifusa(Phaeophyta): towards understanding their biosynthesis and homoeostasis

Endogenous cytokinins, auxins and abscisic acid inUlva fasciata(Chlorophyta) andDictyota humifusa(Phaeophyta): towards understanding their biosynthesis and homoeostasis

The effect of a seaweed concentrate on the in vitro growth and acclimatization of potato plantlets

Significance of betaines in the increased chlorophyll content of plants treated with seaweed extract

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