Showing papers on "Zeatin published in 1970"
TL;DR: Apical sections of resting potato tubers of the variety Majestic, which is known for a long rest-period, were treated for 6 and 24 hours with water or with the cytokinins kinetin or zeatin, and the content of acid inhibitors in extracts of the peelings from cytokinin-treated sections in much lower than in similar extracts from water-treated, resting sections.
Abstract: Apical sections of resting potato tubers of the variety Majestic, which is known for a long rest-period, were treated for 6 and 24 hours with water or with the cytokinins kinetin or zeatin. The cytokinin-treatment breaks the rest-period very rapidly. The buds begin to sprout already after 2–3 days. The content of acid inhibitors (the β inhibitor) in extracts of the peelings from cytokinin-treated sections in much lower than in similar extracts from water-treated, resting sections. Already 6 hours after the beginning of the treatment, differences in inhibitor content can be demonstrated.
62 citations
TL;DR: The results suggest that the inhibition of growth in the axes by ABA is not due to its inhibition of DNA synthesis, and it is suggested that one possible effect of ABA may be at the level of translation.
Abstract: Abscisic acid (ABA) is an effective inhibitor of cell elongation in excised embryonic bean axes whether added prior to or after the initiation of cell elongation. Zeatin partially reverses this growth inhibition. ABA inhibits (32)P incorporation into ribosomal RNA, transfer RNA, and DNA but not into the tenaciously bound fraction of elongating axes in a manner resembling 5-fluorouracil, a compound which does not inhibit axis growth. The methylated albumin on kie-selguhr elution profiles of nucleic acids obtained from axes treated with either ABA, 5-fluorouracil, or a combination of the two are similar, and zeatin treatment has little apparent effect on these results. Our results suggest that the inhibition of growth in the axes by ABA is not due to its inhibition of DNA synthesis.ABA (1.9 x 10(-5)m) inhibits growth by 30 and 70% within 1 and 2 hours, respectively, after its addition to elongating axes. Its kinetics of inhibition are similar to those obtained with cycloheximide, and both compounds are more effective than 8-azaadenine. Based on these results, it is suggested that one possible effect of ABA may be at the level of translation.
47 citations
TL;DR: In this paper, 14 compounds were tested for relative promotion of cell division and growth (cytokinin) activity in the tobacco bioassay, and the results suggested that 2-substituted-N 6 -(hydroxy)isopentenylaminopurines were generally less active than their unsubstrained couterparts.
45 citations
TL;DR: Excised shoot apices of Rosa multiflora grew into plantlets but two other cytokinins, kinetin and 6-(3-methylbut-2-enyl)aminopurien, were ineffective and auxins or gibberellic acid were either inhibitory or had no effect on differentiation.
Abstract: Excised shoot apices (0.6 or 1.0 mm long) of Rosa multiflora were grown in axenic culture on defined media including auxins, gibberellic acid and cytokinins. In the presence of zeatin (10(-8)-10(-7)M) and 6-benzylaminopurine (10(-7)-10(-6) M) apices grew into plantlets but two other cytokinins, kinetin and 6-(3-methylbut-2-enyl)aminopurien, were ineffective. Auxins or gibberellic acid were either inhibitory or had no effect on differentiation.
35 citations
TL;DR: Extracts of immature seeds of watermelon contain three cytokinins which are adsorbed on Dowex 50W ion exchange resin and the Rf of the fastest moving factor is similar to that of zeatin and the chromatographic properties of the second factor are believed to be new to literature.
Abstract: Extracts of immature seeds of watermelon contain three cytokinins which are adsorbed on Dowex 50W ion exchange resin. The Rf of the fastest moving factor is similar to that of zeatin. The slowest moving factor is insoluble in n-butanol and shows some resemblance to zeatin ribotide. The chromatographic properties of the second factor are, however, different from those of any of the known cytokinins and is believed to be new to literature.
25 citations
TL;DR: Extracts of seeds of pumpkin contain three chromatographically distinguishable cytokinins which are held on Dowex 50-W and are extractable by ethanol and n-butanol, but the R(F) values of the other two active compounds do not match with those of any of the known natural cytokers.
Abstract: Extracts of seeds of pumpkin (Cucurbita pepo Linn.) contain three chromatographically distinguishable cytokinins which are held on Dowex 50-W and are extractable by ethanol and n-butanol. Two of the active factors are precipitable by silver nitrate at acidic pH. The chromatographic behavior and the spectral characteristics of one of these cytokinins are similar to those of zeatin. However, the R(F) values of the other two active compounds do not match with those of any of the known natural cytokinins.
24 citations
TL;DR: Of several cytokinins tested, zeatin and 6-benzylaminopurine are the most potent and can bring about the same affect as EDDHA when added in a medium containing excess of iron, Interestingly, when both EDD HA and a cytokinin are provided together, flowering occurs even in the medium containing normal level of iron.
Abstract: Lemna paucicostata HEGELM., a short-day plant, can be induced to flower under long days by provision of cytokinins in the medium. Of several cytokinins tested, zeatin and 6-benzylaminopurine are the most potent. They are effective when added in a medium containing excess of iron and thus can bring about the same affect as EDDHA. Interestingly, when both EDDHA and a cytokinin are provided together, flowering occurs even in the medium containing normal level of iron. Other cytokinins such as SD 8339, kinetin and 6-(δ,δ-dimethylallylamino)-purine are also effective in medium containing a slightly higher level of ferric citrate. In contrast to cytokinins, indole-3-acetic acid and gibberellic acid are not only ineffective by themselves, but even nullify the inductive effect of cytokinins on flowering. Growth retardants such as CCC and abscisic acid have been found to inhibit flowering at high levels.
22 citations
TL;DR: The evidence shows the range of factors that affect the accumulation of solutes in cells as they grow and is to be contrasted with conventional observations on mature cells held in steady states under conditions that preclude all growth and when only a single ionic species is followed over a very short interval of time.
Abstract: The responses of carrot explants to various growth-promoting agents and to certain trace elements with which they interact have been investigated. A great range in the metabolic behavior of the tissue may be brought about in this way. The responses to the exogenously applied substances are described in terms of the growth of the carrot explants in fresh weight and number of cells and also in terms of their metabolism, as shown by the final content and composition of the non-protein N compounds, by the relations between protein and non-protein (alcohol-soluble) N and by the content of nucleic acid in the cultured tissue.The growth-promoting agents employed consisted of (1) the balanced complex of factors found in coconut milk, (2) an active isolate from Aesculus (AFaesc), which is one of a class of growth factors (AF1) that interact with inositol (AF1+inositol) and which in this sense comprise growth-promoting System I, (3) the substance zeatin (Zeat) which is typical of a class of active factors (AF2) that interact with indoleacetic acid (AF2+IAA) and which, therefore, function as a growth promoting complex termed System II in the culture of carrot tissue.The carrot explants stimulated by coconut milk grew better than those stimulated by the other combinations of growth factors and they converted their soluble N more effectively to protein. The growth, whether it was induced by coconut milk or by System I or II, and other specific effects attributable to the growth factors employed were markedly affected also by the elements iron and molybdenum.The carrot explants that had responded to coconut milk emphasized alanine in their soluble, non-protein, nitrogenous pool, whereas those subjected to the active components of System I or of System II as clearly emphasized glutamine as the prominent non-protein, nitrogen-rich compound.The partial effects due to the component parts of System I (AFaesc or inositol) and to the component parts of System II (Zeat. or IAA), as these interacted also with iron and molybdenum in an otherwise trace element free basal medium (B (**)), revealed a pattern of interlocking effects, due to trace elements and to growth factors, upon the metabolism (especially the nitrogen metabolism) of the aseptically cultured carrot explants. These effects show that the individual growth factors do not act alone and that their implications are far reaching. The interactions between growth promoting Systems I and II and their component parts, with each other, with various environmental factors, and especially with trace elements constitute a network, or a matrix, of parameters that will merit further investigation to reveal all that is required to control the growth and metabolism of carrot cells.
11 citations
TL;DR: In this article, the cytokinin containing extracts of young apples and of coconut milk were purified and subjected to chemical treatments designed to modify the chemical natures of the cyclokinins.
Abstract: Cytokinin containing extracts of young apples and of coconut milk were purified and subjected to chemical treatments designed to modify the chemical natures of the cytokinins Chromatographic comparisons were then made between the cytokinins of the treated and untreated extracts and zeatin and zeatin nucleoside
10 citations