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 auxin level is a critical determinant for in vitro adventitious shoot regeneration in potato ( Solanum tuberosum L.)

Abstract: Endogenous levels of indole-3-acetic acid (IAA) were determined in the internodal explants of Indian tetraploid potato cultivars (cvs) viz., Kufri Sutlej (K.Sutlej) and Kufri Giriraj (K.Giriraj). Seven fold higher level of endogenous IAA was recorded for cv K.Sutlej over cv K.Giriraj. As a result, perhaps there was a callusing response from the cut end of the internodal explants of both the cvs in the MS basal medium. The extent of callusing was relatively higher in cv K.Sutlej when compared to that in K.Giriraj. The callusing response was inhibitory to shoot morphogenesis. Inclusion of an established anti-auxin, 2,3,5-tri-iodobenzoic acid (TIBA) in the regeneration medium facilitated a high frequency adventitious shoot regeneration response with lower cytokinin levels. Murashige and Skoog (MS) medium containing TIBA at 2.5 mg l−1 and 0.25 mg l−1 zeatin evoked a 100% regeneration response (4.5 shoot buds per explant) in cv K.Sutlej within 20–25 days. However, in cv K.Giriraj, which had lower levels of endogenous IAA, 80% regeneration response (1.4 shoot buds per explant) was recorded in an extended period of 40–45 days on a medium containing 0.5 mg l−1 TIBA and 0.1 mg l−1 zeatin. Although, TIBA and zeatin induced shoot bud formation, it failed to support sustained growth of the regenerated shoots in cv K.Giriraj. Hence, 0.01 mg l−1 α-naphthaleneacetic acid (NAA) with a relatively higher concentration of zeatin (1.0 mg l−1) were used for sustained shoot regeneration (3.3 shoot buds per explant) within 25 days. From our results, it is evident that there was a difference in the requirement of exogenous zeatin levels required to induce a regeneration response in two cultivars of potato and this is attributed to the variable levels of endogenous IAA.

Cytokinins extracted from pinto bean fruit.

Abstract: Extracts from various parts of Phaseolus vulgaris L. var. Pinto plants were found to exhibit cytokinin activity with the highest levels present in extracts of the fruit tissue. To separate the cytokinins present in the fruit, extracts were chromatographed in several solvent systems. Bioassays of chromatograms indicated the presence of active factors in those regions of migration associated with several known N-6-substituted aminopurines.Ultraviolet and mass spectral studies confirm the presence of a mixture of N-6-substituted aminopurines in the active material isolated by cation exchange resin chromatography. The evidence strongly supports the conclusions that dihydrozeatin is naturally occurring as the free base and possibly as a ribonucleoside. Further, zeatin appears to occur mainly as a glycosidic compound which is altered by KMnO(4) treatment and is hydrolyzed under acid conditions.

Dynamics of production of trans -zeatin and trans -zeatin riboside by immobilized cytokinin-autonomous and cytokinin-dependent tobacco cells

Abstract: Two strains of cultured tobacco cells (Nicotiana tabacum L. cv. Wisconsin 38) differing in their requirement for exogenous cytokinins (cytokinin-dependent and cytokinin-autonomous) were immobilized on polyphenylenoxide (Sorfix) activated with glutaraldehyde. Columns packed with immobilized cells were continually eluted with diluted Murashige and Skoog's medium lacking or supplemented with synthetic cytokinin (6-benzylaminopurine; BA). Purified samples of column eluates were fractionated by HPLC, andtrans-zeatin (t-Z) andtrans-zeatin riboside (t-ZR) content was estimated by enzyme immunoassay. Both cytokinin-autonomous and cytokinin-dependent tobacco cells produced and excretedt-Z and its riboside, and there were significant quantitative differences between the strains. The steady-state excretion rate oft-Z was 19.8 ng · g−1 dw · h−1 and 4 ng · g−1 dw · h−1, respectively, and that oft-ZR 4 ng · g−1 dw · h−1 and 1 ng · g−1 dw · h−1, respectively. Exposure of cytokinin-dependent cells to BA after 72 h of starving for this synthetic cytokinin caused temporary increase in excretion of both zeatin and its riboside. After the application of 5 μM BA for 24 h, the excretion rate oft-ZR reached 5 ng · g−1 dw · h−1 (5-fold increase), and that oft-Z achieved 12 ng · g−1 dw · h−1 (3-fold increase). The elevation oft-Z excretion was delayed about 13 h compared witht-ZR excretion, which started increasing almost immediately after BA application. A pulse of BA in lower concentration (1.5 μM for 30 h) provoked lower response.

[Sugar beet (Beta vulgaris L.) morphogenesis in vitro: effects of phytohormone type and concentration in the culture medium, type of explants, and plant genotype on shoot regeneration frequency].

Abstract: In vitro regeneration techniques have been optimized for seven strains and cultivars of sugar beet (Beta vulgaris L.) bred in Russia. The frequency of shoot regeneration from somatic cells and tissues of sugar beet varies from 10 to 97% depending on the explant type, culture-medium composition, and genotype. The in vitro regeneration potential has been estimated in plants with different genotypes. The effect of medium composition (phytohormones and carbohydrates) on the frequency of the formation of a morphogenic callus competent for plant regeneration has been determined. The effect of the types and concentrations of various cytokines (zeatin, kinetin, and 6-benzylaminopurine) on direct shoot regeneration from cotyledon nodes has been estimated. The culture-medium composition has been optimized for direct shoot regeneration from petioles. The effects of different concentrations of abscisic acid on the frequency of shoot regeneration from a morphogenic callus has been studied. Micropropagation has been used to obtain petiole explants and reproduce the shoots obtained by direct regeneration from cotyledonnodes, petioles, and calluses. Improved shoot-regeneration methods can be used for both agrobacterial and bioballistic genetic transformation of the sugar beet genotypes studied.