Zeatin

About: Zeatin is a research topic. Over the lifetime, 2467 publications have been published within this topic receiving 64092 citations. The topic is also known as: Zeatin & (E/Z)-zeatin.

Stable integration and expression of a plant defensin in tomato confers resistance to fusarium wilt

Abstract: Plant defensins are small cysteine-rich peptides which belong to a group of pathogenasis related defense mechanism proteins. The proteins inhibit the growth of a broad range of microbes and are highly stable under extreme environmental stresses. Tomato cultivation is affected by fungal disease such as Fusarium wilt. In order to overcome fungal damages, transgenic tomato plants expressing the Medicago sativa defensin gene MsDef1 under the control of the CaMV 35S promoter were developed. The Fusarium-susceptible tomato (Lycobersicum esculentum Mill) cultivar CastleRock was used for transformation to acquire fungal resistance. Hypocotyl with a part of cotyledon (hypocotyledonary) for young tomato seedlings were used as an explant material and transformation was performed using the biolistic delivery system. Bombarded shoots were selected on regeneration medium supplemented with hygromycin and suitable concentrations of BA, zeatin ripozide and AgNO3. Putative transgenic plantlets of T0 were confirmed by PCR...

Mass Spectroscopic Identification of Cytokinins Glucosyl Zeatin and Glucosyl Ribosylzeatin from Vinca rosea Crown Gall

Abstract: Mass spectrographic and chemical studies of the permethyl and trimethylsilyl ethers of two new cytokinins isolated from Vinca rosea crown gall callus cultures by Peterson and Miller (Plant Physiol 59: 1026-1028) indicate that they are 6-(4-0-beta-d-glucopyranosyl-3-methyl-trans-but-2-enylamino) purine (glucosyl zeatin) and 9-beta-d-ribofuranosyl-6 (4-0-beta-d-glucopyranosyl-3-methyl-trans-but-2-enylamino) purine (glucosyl ribosylzeatin). The nature of the mass spectra of the permethylated cytokinins suggests that these derivatives may have considerable utility in the detection of low levels of cytokinins in plant material.

Cytokinin translocation and metabolism in lupin species. I. Zeatin riboside introduced into the xylem at the base of Lupinus angustifolius stems.

Abstract: The principal cytokinins in xylem exudate of blue lupin (Lupinus angustifolius L.) identified by radioimmunoassay and mass spectrometry were zeatin riboside (ZR), dihydrozeatin riboside and zeatin, but cytokinin O-glucosides and nucleotides were also present. Radioactive [3H]ZR was supplied to the transpiration stream of both derooted and intact blue lupin plants. The distribution of methanol-extracted radioactivity throughout the shoot and the identities of 3H-labelled metabolites were determined; for the latter work, a new bilayer thin-layer chromatography system was developed. In derooted plants supplied with ZR for about 20 h, radioactivity per unit fresh weight of tissue was greatest in the peduncle, stem and axillary shoots and least in the seed. Differences in metabolism were more marked between tissue types than within tissues of different maturity. The principal metabolites in derooted plants (ZR supplied for up to 24 h) were: in laminae, O-glucosyldihydrozeatin, lupinic acid, dihydrozeatin riboside and adenosine; in petioles, dihydrozeatin riboside and adenosine; in pod walls, cytokinin nucleotides, dihydrozeatin riboside, adenine and adenosine; in developing lateral shoots, cytokinin nucleotides; in stem, dihydrozeatin riboside, dihydrozeatin and cytokinin nucleotides. Apart from adenosine, no metabolites could be identified with certainty in seed. In experiments with intact plants conducted over a longer period (plants extracted 2 days after 30 h uptake), metabolism was more extensive but, in all tissues except seed, low percentages of radioactivity were still due to metabolites with an intact zeatin moiety (most frequently O-glucosyldihydrozeatin and lupinic acid). Free zeatin and dihydrozeatin were not found in any tissue and their ribosides were detected with certainty only in pod walls (<2% of extracted 3H). Extraction with 0.5 N KOH after extraction with methanol yielded, on average, an additional equal amount of radioactivity due to nucleotides of adenine and guanine. Features of the translocation studies include: (1) the direct lateral movement of ZR and/or related cytokinins from xylem to bark which was established by bark ringing experiments; (2) the relatively high level of radioactivity per unit tissue fresh weight in developing lateral shoots; (3) the lack of appreciable movement to the seed although the cytokinin reached the pod walls and was partially conserved there; (4) the disproportionately high retention of radioactivity by the petioles which increased with leaf age; (5) changes in ZR metabolites in laminae associated with age; (6) the detection of a new nucleotide metabolite of ZR in pod walls, bark and lateral shoots; this appears to be a transient metabolite with an intact ZR moiety and may be involved in ZR uptake and/or transport. The studies of ZR translocation and metabolism are discussed in relation to sequential leaf senescence, the proposal that developing seeds accumulate xylem cytokinins, and the origin of phloem cytokinins.

In Vitro Culture of Lingonberry (Vaccinium vitis-idaea L.)

Abstract: Shoots of three lingonberry (Vaccinium vitis-idaea L.) cultivars, ‘Regal’, ‘Splendor’, and ‘Erntedank’ and two clones from natural stands in Newfoundland were initiated in vitro from shoot tip and nodal explants on modified Murashige and Skoog (MS) medium containing the plant growth regulators N6-[2-isopentenyl]adenine (2iP) (12.3 μM) or zeatin (5.7 μM). Zeatin was more effective than 2iP, and induced proliferation of 2 to 3 times as many shoots in ‘Regal’ as 2iP. Out of four media tested for shoot proliferation, modified MS medium was found more effective than the Woody Plant Medium for shoot multiplication. With all three cultivars, a reasonable balance in terms of shoot multiplication rate and desirable growth characteristics was attained in a new medium. Nodal explants of the two clones cultured on the modified MS medium with 12.3 μM 2iP produced 4 to 6 healthy axillary shoots per explant in clone 1 and 2 to 4 shoots in clone 2. Shoots rooted well ex vitro directly on a 2 peat: 1 perlite (v/v...