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.

Endogenous cytokinin levels during early fruit development of macadamia

Abstract: Cytokinins play a central role in fruit set and development, with many plants accumulating high concentrations of endogenous cytokinins in developing fruits, and applied cytokinins being used to induce fruit set or parthenocarpic fruit development. Cytokinin application to flowers or immature fruit of macadamia increases initial fruit set and delays fruit abscission, without affecting final fruit set. This study quantified and determined the timing of endogenous cytokinin accumulation in macadamia flowers and immature fruit, to assist in developing a cytokinin treatment to improve fruit set and kernel quality. Flowers and very young fruit contained little cytokinin but levels rose greatly between 3 and 10 weeks after anthesis. Zeatin and zeatin riboside were the predominant cytokinins at 10 weeks postanthesis, with zeatin riboside concentrations being 20 - 230 times higher than concentrations detected immediately after anthesis. Cytokinin accumulation coincides with the period of maximum endosperm volume in macadamia which, along with the predominance of zeatin and zeatin riboside, conforms to the general pattern of accumulation in developing fruits of many other plants. The very high cytokinin concentrations at this stage may explain the inability of pre- or post-anthesis cytokinin applications to increase fruit retention of macadamia beyond 10 weeks post-anthesis.

In vitro plantlet regeneration from cotyledon, hypocotyl and root explants of hybrid seed geranium

Abstract: In vitro plantlet regeneration systems for the seed geranium (Pelargonium x hortorum Bailey) using cotyledon, hypocotyl and root explants were optimized by studying the influence of seedling age, growth regulators and excision orientation on organogenesis. Indole-3-acetic acid combined with zeatin yielded the highest rate of shoot production on cotyledon explants (0.2–2 shoots per explant). More shoots were produced on explants cut from the most basal region of cotyledons from 2 to 4-day-old seedlings than from older seedlings or more distal cut sites. Hypocotyl explants produced the highest number of shoots, up to 40 shoots per explant, on indole-3-acetic acid (2.8–5.6 mM) + zeatin (4.6 mM) or thidiazuron (4.5 mM). Maximum shoot formation (0.3–1.4 shoots per explant) on root explants occurred when they were cultured on medium containing zeatin. Regenerated shoots rooted best on a basal medium containing no growth regulators. There were substantial differences among cultivars in shoot formation from each of the explant systems.

Contents of abscisic acid and cytokinins in shoots during dehydration of wheat seedlings

Abstract: Accumulation of ABA in shoots during 30-min dehydration of wheat seedlings was accompanied by the decline in the content of zeatin nucleotide and the accumulation of zeatin 9-N-glucoside. The total content of zeatin derivatives as well as the content of free base of zeatin remained almost constant.

Synthesis and Cytokinin Activity of New Zeatin Derivatives

Abstract: The analogue of zeatin bearing a vinylic fluorine atom and its geometrical isomer were synthesized. The fluorine atom exerts a favorable influence on cytokinin activity in the fluoro analogue of cis-zeatin, but not in the fluoro analogue of zeatin itself. Another series of zeatin derivatives in which the methyl group was replaced by alkyl (ethyl, propyl, and isopropyl), phenyl, and benzyl groups were also obtained. The ethyl analogue was found to be more active than zeatin, while the others were inactive or slightly active. Keywords: Cytokinins; fluoro compounds; synthesis; biological activity