Chemistry and Physiology of Kinetin-Like Compounds
01 Jun 1967-Annual Review of Plant Biology (Annual Reviews 4139 El Camino Way, P.O. Box 10139, Palo Alto, CA 94303-0139, USA)-Vol. 18, Iss: 1, pp 349-364
About: This article is published in Annual Review of Plant Biology.The article was published on 1967-06-01. It has received 193 citations till now. The article focuses on the topics: Kinetin.
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TL;DR: The principal metabolites formed from zeatin by the roots of intact Z. mays seedlings were adenosine-5′-phosphate, zeat in riboside, adenine,Adenosine and an unknown compound termed Y.mays which was isolated and identified as 9-glucosylzeatin.
Abstract: [3H]Zeatin was supplied through the transpiration stream to radish (Raphanus sativus L.) seedlings with roots excised. Formation of dihydrozeatin was not detected but numerous other metabolites were formed, including adenine, adenosine, AMP, zeatin riboside and zeatin riboside-5′-monophosphate. However, in labelled seedlings which had been left in water for 15 h, an unknown compound (raphanatin) was the dominant metabolite and accounted for about 25% of the total radioactivity extracted. A procedure for the isolation of this metabolite was devised and yielded 70 μg from 1600 seedlings. Raphanatin was characterized by mass and ultraviolet spectra and has been identified as 7-glucosylzeatin. It is an active and very stable metabolite which was located mainly in the cotyledon laminae and may be a storage form of the hormone. In contrast, labelled nucleotides, the other major metabolites of zeatin, were largely confined to the hypocotyls and petioles. Zeatin riboside-5′-monophosphate was the dominant metabolite in hypocotyls of de-rooted seedlings supplied with zeatin for 0.5–2 h. The majority of the radioactivity in the xylem sap was due to zeatin, but about 10% was present as zeatin riboside; nucleotides accounted for less than 10% of the radioactivity and labelled raphanatin was not detected.
308 citations
TL;DR: Developmental effects of end-of-day red and far red light were studied in the controlled environment laboratory and the red-irradiated plants developed branches from axils of lower leaves, while no branching occurred on plants that received far red radiation last each day.
Abstract: Shifts in spectral distribution of light were determined within and below a canopy of field-grown burley tobacco (Nicotiana tabacum L. cv. Burley 21). The leaves transmitted much far red light relative to red and blue light. Thus, shaded leaves received more far red light, relative to red and blue, than was received by unshaded leaves. Under field conditions, tobacco plants within rows grew taller than did those at the west end of rows.Developmental effects of end-of-day red and far red light were studied in the controlled environment laboratory. Plants that received far red light last, each day, resembled plants shaded by other plants. The far red-irradiated plants developed longer internodes, were lighter green in color, and had thinner leaves than the red-irradiated ones. Plants of both treatments had the same number of leaves on the main axis. However, the red-irradiated plants developed branches from axils of lower leaves, while no branching occurred on plants that received far red radiation last each day.
251 citations
TL;DR: Present evidence indicates that only the root systems of plants have been shown conclusively to synthesize cytokinins, and although most of these compounds are apparently exported to the shoot via the xylem, there are indications that more attention should be given to the possibility of translocation through the phloem.
Abstract: Present evidence indicates that only the root systems of plants have been shown conclusively to synthesize cytokinins. Although most of these compounds are apparently exported to the shoot via the xylem, there are indications that more attention should be given to the possibility of translocation through the phloem. Within mature leaves the cytokinins derived from the roots are converted to inactive or storage forms by means of glucosylation. While it would appear that glucosylation could occur in all living plant cells whenever the cytokinins are no longer required for active growth, and could provide the plant with a potential reservoir of cytokinins, very little is known with regard to the transport and reutilisation of these compounds.
226 citations
01 Jan 2008
TL;DR: Hormones in plants differ from most of those in animals by having pleiotropic effects; that is, they are involved in the control of a wide range of developmental processes, but the effect of a hormone on any developmental process depends on the species.
Abstract: Hormones in plants differ from most of those in animals by having pleiotropic effects; that is, they are involved in the control of a wide range of developmental processes. At the same time the effect of a hormone on any developmental process depends on the species. For example, ethylene inhibits growth in dicotyledons and most monocotyledons but is promotory in deepwater rice and other hydrophytes. Moreover, two or more hormones can interact synergistically or antagonistically in many circumstances. Equally, any given hormone may affect the biosynthesis or metabolism of another, thus affecting endogenous levels. The issue is further complicated by the fact that environmental factors e.g. light, water status, wounding, pathogens may modify responses and indeed hormone levels themselves. The reason for this appears to be that hormones (and growth regulators) and environmental factors share many components in their transduction chains (i.e. the very early events which occur after the signal abiotic or biotic is perceived by the plant tissue). These transduction chains interact to produce an integrated response.
206 citations
Cites methods from "Chemistry and Physiology of Kinetin..."
...The dependence of some callus cultures on cytokinin for cell division has been used as the basis of a sensitive bio-assay for cytokinins (Miller, 1963; Linsmaier and Skoog, 1965; Letham, 1967)....
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TL;DR: In this paper, a modified Amaranthus betacyanin bioassay was used for the bioassaying of pure cytokinin standards and celery seed extracts containing cytokinIN activity.
Abstract: Pure cytokinin standards and celery seed extracts containing cytokinin activity were bioassayed using a modified Amaranthus betacyanin bioassay The assay is very rapid and requires no special sterile precautions
206 citations
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