Topic
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.
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TL;DR: Results suggest that substitution of the 8 position with a hydroxyl group causes less decrease of cytokinin activity than substitution of both the 2 and 8 positions with Hydroxyl groups.
Abstract: 8-Hydroxy and 2,8-dihydroxy derivatives of the cytokinins, 6-(4-hydroxy-3-methyl-trans-2-butenylamino)purine and N-6-(increment -2-isopentenyl)adenine, have been biosynthesized by xanthine oxidase oxidation. 8-Hydroxy derivatives have been shown to be the major intermdeiates. These compounds were tested for cytokinin activity in the tobacco bioassay. The results suggest that substitution of the 8 position with a hydroxyl group causes less decrease of cytokinin activity than substitution of both the 2 and 8 positions with hydroxyl groups.
22 citations
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TL;DR: An efficient and simple plant regeneration system via organogenesis from leaf segments of persimmon cultivars ‘Fuyu’ and ‘Nishimurawase’ has been developed and dark incubation was the most effective condition to successfully influence shoot regeneration in both cultivars.
Abstract: An efficient and simple plant regeneration system via organogenesis from leaf segments of persimmon (Diospyros kaki Thunb.) cultivars ‘Fuyu’ and ‘Nishimurawase’ has been developed. The regeneration capacity was influenced by the culture vessels, gelling agents, plant growth regulators, and light conditions. Leaf explants taken from in vitro shoots were cultured on a modified Murashige and Skoog medium (MS1/2N), for 16 wk without transfer to fresh medium. Adventious shoots appeared after 4 and 8 wk in culture of ‘Nishimurawase’ and ‘Fuyu’ tissues, respectively. The culture of leaf explants in Erlenmeyer flasks with medium containing 4 g l−1 agar enhanced shoot formation in comparison to media with increased agar concentrations. Optimal shoot regeneration was obtained with 5 mg l−1 (22.8 μM) zeatin and 0.1 mg l−1 (0.05 μM) indole-3-butyric acid (IBA) for ‘Nishimurawase’, and 10 mg l−1 (45.6 μM) zeatin and 0.1 mg l−1 (0.05 μM) IBA for ‘Fuyn’. Shoot regeneration frequencies in both cultivars were 100%, and shoot numbers per explant reached up to 9.2 for ‘Nishimurawase’ and 2.2 for ‘Fuyu’. Dark incubation during the first 4–5 wk was the most effective condition to successfully influence shoot regeneration in both cultivars. While dark incubation was essential for adventitious shoot formation by ‘Fuyu’, it was only slightly beneficial to ‘Nishimurawase’. More than 80% of the regenerated shoots rooted within 4 wk on hormone-free MS1/2N demium after having been dipped for 30 s in 250 mg l−1 (1.1. mM) IBA solution.
22 citations
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TL;DR: A survey of 30 species of woody plants in 20 families of dicotyledonous angiosperms indicated that the ability to accumulate io6Ade in 24-hr feeds with 30 μM i 6Ade was restricted to certain systematic groups—e.g., order Ericales, families Oleaceae and Rubiaceae.
Abstract: Tissue cultures of Actinidia kolomikta can be maintained as callus through repeated passages on a nutrient medium devoid of cytokinin but containing inorganic nutrients, sucrose, and other basal organics plus auxin. Under these conditions, actively growing callus contained 2 and 0.5 nmol of the cytokinins zeatin [io6Ade; 6-(4-hydroxy-3-methylbut-2-enylamino)purine] and N6-(Δ2-isopentenyl)adenine (i6Ade), respectively, per gram (fresh weight). When tissues were transferred from cytokininless medium to 30 μM i6Ade, endogenous io6Ade increased linearly to 160 nmol/g (fresh weight) during 8 hr, and i6Ade increased to 5 nmol/g (fresh weight) in 2 hr and then declined. The apparent Km for i6Ade in A. kolomikta and Actinidia chinensis × Actinidia arguta callus and in tissue slices of A. arguta stems was 12 μM. In addition, the reaction(s) converting i6Ade to io6Ade was O2-requiring and specific for i6Ade versus N6-(Δ2-isopentenyl)adenosine (i6A). When A. kolomikta callus was fed 30 μM i6A, io6Ade increased and reached a concentration corresponding to 6 nmol/g (fresh weight) in 8 hr. Ribosylzeatin (io6A) did not increase. Under N2 during i6A feeds, i6A accumulated rather than being metabolized to i6Ade, suggesting that i6A normally may be metabolized via i6AMP and i6Ade to io6Ade. A survey of 30 species of woody plants in 20 families of dicotyledonous angiosperms indicated that the ability to accumulate io6Ade (≥10 nmol/g) in 24-hr feeds with 30 μM i6Ade was restricted to certain systematic groups—e.g., order Ericales, families Oleaceae and Rubiaceae. This suggests that plants may differ in their pathways for io6Ade biosynthesis and that cytokinin biochemistry has potential as a taxonomic character above the species and genus levels.
22 citations
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TL;DR: In this paper, the effect of different cytokinins on shoot proliferation and biosynthesis of caffeic acid derivatives in Dracocephalum forrestii in vitro culture was analyzed using UPLC-PDA-ESI-MS.
Abstract: The current study estimates the effect of different cytokinins on shoot proliferation and biosynthesis of caffeic acid derivatives in Dracocephalum forrestii in vitro culture. The shoots were grown on Murashige and Skoog (MS) agar medium with 1 µM indole-3-acetic acid (IAA) and different content of 6-benzyloaminopurine (BAP), zeatin, kinetin (1, 2, 4, 8, 18 µM) or thidiazuron (TDZ) (0.1, 0.2, 0.5, 1, 2 µM). The highest multiplication rate (about seven shoots and/or buds per explant) was obtained after 4 weeks of culture on MS medium with 1 µM IAA and 8 or 16 µM BAP. Optimal biomass of plant material was also received on the same media. The identity of the compounds present in the hydromethanolic extracts from D. forrestii shoots grown on cytokinin-supplemented media was confirmed using UPLC–PDA–ESI–MS method. The analysis revealed the presence of nine metabolites recognized as caffeic acid derivatives. The content of the predominant phenolic acids in the extracts, i.e. rosmarinic acid (RA) and salvianolic acid B (SAB), was determined with UHPLC. The highest yield of RA was found in shoots cultivated in the medium containing 1 µM IAA and 2 µM BAP (18.7 mg/g DW). The highest level of SAB (5.3–5.9 mg/g DW) was identified in multiple shoots grown in the presence of 1 µM IAA and 0.5–1 µM TDZ or 2 µM BAP.
22 citations
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TL;DR: Axillary buds from 3-year-old Carica pubescens Lenné et Koch (highland papaya) fruit-bearing plants grown in the greenhouse were cultivated in NN-medium supplemented with different growth regulators naphthaleneacetic Acid and indoleacetic acid in combination with Zeatin, benzyladenine, Kinetin and thidiazuron.
Abstract: Axillary buds (2 mm) from 3-year-old Carica pubescens Lenne et Koch (highland papaya) fruit-bearing plants grown in the greenhouse were cultivated in NN-medium supplemented with different growth regulators naphthaleneacetic acid and indoleacetic acid in combination with Zeatin, benzyladenine, Kinetin and thidiazuron. Several responses were observed within 2–3 months; namely, sprouting of the preformed axillary buds, bud branching into multiple shoots, callus formation at the basal end of the explant and somatic embryogenesis in the preformed callus. Somatic embryogenesis was frequent in most of the tested growth regulator combinations, with the exception of thidiazuron which showed no effect. A much higher yield of somatic embryos could be obtained in suspensions. Somatic embryogenesis was enhanced by the occurence of adventive embryogenesis on single embryos as globular embryo clusters. This was observed in cell suspensions initially grown in a WPM-medium with 2,4-dichlorophenoxyacetic acid, or in combination with benzyladenine or zeatin, for 6 days, then maintained in a growth regulator-free medium under continuous agitation (50 RPM) on an orbital shaker for 3 months. Single cells grown in the absence of 2,4-dichlorophenoxyacetic acid did not initiate embryogenesis and de-differentiated into callus. Plantlets were recovered after transfer of mature embryos from cell suspensions into Magenta flasks. In a second subculture, adventitious embryogenesis occurred spontaneously in clusters at the globular embryo stage under the same growth conditions, yielding a high number of embryos. The culture conditions described above allowed initiation of a large number of somatic embryos directly from cell suspensions through adventive somatic embryogenesis and indirectly from callus on axillary buds.
22 citations