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.

High efficiency organogenesis and analysis of genetic stability of the regenerants in Solanum melongena

Abstract: A novel protocol for plant regeneration from cotyledon explants of eggplant (Solanum melongena) reducing concentration of sucrose was established. The most efficient bud induction medium consisted of Murashige and Skoog (MS) medium supplemented with 2.0 mg dm−3 zeatin, 0.1 mg dm−3 indoleacetic acid and 10 g dm−3 sucrose. After 15 d, the shoot buds were fragmented and transferred to the shoot elongation MS supplemented with 1.0–2.0 mg dm−3 gibberellic acid and 4.0–8.0 mg dm−3 AgNO3, which promoted shoots elongation. The genetic stability of the regenerated plants was analyzed by flow cytometry, RAPD and SSR molecular markers. The results indicated that almost no somaclonal variation was detected among the regenerants.

Regeneration of tepals, stamens and ovules in explants from perianth of Hyacinthus orientalis L. importance of explant age and exogenous hormones.

Abstract: Regeneration of tepals, stamens and ovules from perianth explants of Hyacinthus orientalis L. in different developmental stages could be controlled by means of exogenous hormones. Perianth explants in a relatively early stage of development were competent for differentiation of tepals on Murashige and Skoog (MS) medium supplemented with 2 mg·1(-1) N(6)-benzylaminopurine (BAP) or zeatin and 0.1 mg·1(-1) 2,4-dichlorophenoxyacetic acid (2,4-D). Perianth explants in a later stage of development regenerated stamens and ovules, and marked difference was observed in the activity of BAP and zeatin in this regard. Zeatin stimulated more strongly stamen formation, while BAP enhanced ovule formation. Thus, stamens were formed when the explants were cultured for four months on medium with 2 mg·1(-1) BAP and 0.1 mg·1(-1) 2,4-D and then transferred to medium with 0.2 mg·1(-1) zeatin and 0.005 mg·1(-1) 1-naphthaleneacetic acid. On the other hand, differentiation of ovules occured in explants cultured for two weeks on the former medium and then transferred to medium with 0.1 mg·1(-1) BAP and 0.01 mg·1(-1) 2,4-D. Although ovule formation could also be obtained with 2 mg·1(-1) BAP alone, it was substantially enhanced by the presence of 0.1 mg·1(-1) 2,4-D in the medium in the early stages of culture. The results demonstrate the importance of both the developmental stage of the source organ from which explants are excised and of the hormone composition of the medium for the regeneration of different floral organs by perianth explants of Hyacinthus.

A Comparison of the Endogenous Cytokinins in the Roots and Xylem Exudate of Nematode-resistant and Susceptible Tomato Cultivars

Abstract: Non-infested roots of a tomato cultivar (Roodeplaat Premier) susceptible to root-knot nema todes contained higher levels of endogenous cytokinins than non-infested roots of a nematode resistant cultivar (Master Fl). In both cultivars nematode infestation increased the cytokinin level in the roots. Sephadex LH-20 fractionation indicated that the xylem exudate of infested susceptible plants contained zeatin and zeatin riboside. In the roots of both cultivars a third compound, which co-eluted with zeatin glucoside, was present. The activity of all three cell division-inducing compounds was higher in the roots of susceptible plants than in roots of nematode-resistant plants. The present results support the hypothesis that cytokinins may be a controlling factor in the development of giant cells.

An improved cytokinin bioassay using cultured soybean hypocotyl sections.

Abstract: This paper describes a modified soybean (Glycine max) tissue culture bioassay for cytokinins. Soybean hypocotyls were grown under sterile conditions and sliced into 1-mm sections. Sections were cultured for 5,9,13, or 22 days on a callus medium with zeatin or other cytokinins. The fresh weight of sections increased with the cytokinin concentration from 0.0005 to 1 mum zeatin; 2-fold concentration differences were readily distinguishable at 9 days. The assay should prove to have several advantages over the conventional soybean callus bioassay including convenience, lower variability between tissue samples, and improved resolution. Its specificity is comparable to that of the soybean callus bioassay.

Amounts of Zeatin and Zeatin Riboside in Xylem Sap of Senscent and Nonsenescent Sorghum

Abstract: Xylem sap from decapitated vegetative and mature plants of nonsenescent ‘Tx2817’ and senescent ‘TxTOOO’ sorghum [Sorghum bicolor (L.) Moench] cultivars was analyzed for cytokinins to determine whether the delayed leaf senescence of nonsenescent sorghums may be associated with transport of greater quantities of cytokinins from roots. Cytokinins were assayed by high-performance liquid chromatography (ultraviolet absorption) with ˡ⁴C-labeled zeatin (Z) as an internal standard. For field-grown plants, the amount of Z + zeatin riboside (ZR) in xylem sap per gram shoot dry weight was 1.51 times higher for the nonsenescent sorghum. Vegetative plants were grown in solution culture for ⊄ 1 mo and then irradiance and N supply were altered for 7 or 8 d prior to collection of sap for 24 h. With high N and high light, Tx7000 and Tx2817 had nearly identical Z + ZR in the sap per gram shoot fresh weight. Treatments of 10% N supply or 50% light reduced growth only slightly. With 10% N, however, Z + ZR averaged 38% of the control for Tx7000 and 59% for Tx2817; with 50% light, Z + ZR averaged 55% of the control for Tx7000 and 136% for Tx2817. Thus, Z and ZR transport from roots to shoots of nonsenescent Tx2817 was less susceptible to reduction by low N and was actually increased by low light. High xylem sap cytokinin contents for Tx2817 with 50% light suggests that its delayed senescence and enhanced resistance to adverse conditions may be due to high cytokinin production by roots when the carbohydrate supply to the roots is reduced. Contribution of the Texas Agric. Exp. Stn. Journal Article no. TA27045.