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.

Callus growth and rooting of cassava (manihot esculenta crantz) stem segments cultured in vitro

Abstract: SUMMARY With the in vitro culture of cassava tissue the optimum sucrose level for callus growth is lower than that for the initiation and growth of roots. Auxin and cytokinin both promote callus growth, the latter by inducing cell division, the former also by stimulating cell elongation. In subcultures cytokinins are obligatory for callus growth, the natural cytokinins, zeatin and 2iP, yielding green tissues. Organ development never occurred in these subcultures. Auxin (NAA) is required for the initiation and growth of roots on the callus. Different cytokinins reduce this rooting effect in various degrees without, however, inducing the initiation of shoot primordia.

Metabolism of [14C]trans-zeatin and [14C]benzyladenine by letached yellow, green and variegated leaves of Schefflera

Abstract: [8-14C]Benzyladenine (BA) and [8-14C]trans-zeatin (tZ) were fed through the petiole to mature, detached green, yellow and variegated leaves of Schefflera arboricola. Recovery of radioactivity from the plant material ranged between 4.2 and 22.1%. More radioactivity was recovered when tZ was applied compared to BA. Green leaves or the green parts of variegated leaves yielded more radioactivity than the yellow leaf material. BA was metabolized much faster than the endogenous cytokinin tZ. It would appear that while lower amounts of radioactivity were present in yellow leaves, as well as in yellow parts of variegated leaves, the rate of cytokinin metabolism was nevertheless faster. Metabolites that were formed to a greater extent in these yellow parts were the nucleotides of both cytokinins. Currently it is not known whether or not cytokinins influence chlorophyll and other pigment development in chimeric variegated leaves.

Plantlet regeneration from primary callus cultures of Lilium brownii F.E.Br. ex Miellez var. giganteum G. Y. Li & Z. H. Chen, a rare bulbous germplasm

Abstract: Lilium brownii F.E.Br. ex Miellez var. giganteum G. Y. Li & Z. H. Chen, an endangered valuable genetic resource, was used to establish and optimize a callus propagation system and to investigate the effects of internal and external phytohormones for the purpose of germplasm conservation. Of the combinations and concentrations of auxins and cytokinins examined, Murashige and Skoog (MS) medium supplemented with 8 g L−1 agar, 30 g L−1 sucrose, 0.45 μM 2,4-dichlorophenoxyacetic acid, 2.69 to 5.37 μM α-naphthaleneacetic acid, and 0.44 μM 6-benzyladenine, 0.45 μM thidiazuron, and 0.28 μM zeatin riboside generated the best results, effectively promoting callus proliferation. Four callus types could be discriminated, of which type A (yellowish, granular) and type B (yellow, medium-granular) were dry, friable, and grew well. Periodic acid-Schiff staining revealed small and regular cells, with numerous starch granules surrounding each nucleus. In culture, callus clumps produced an average of 14.33 shoots under “MS + 7-d-dark–light” treatment with 100% regeneration frequency. Bulblets formed within 60 d after shoot transfer to bulblet formation medium. Type A and B callus was likely to be embryogenic, according to morphology, cytology, and high shoot regenerating capacity. Examination of endogenous phytohormone levels showed that the abscisic acid to indole-3-acetic acid (ABA/IAA) ratio gradually increased with increasing diameter of callus clumps treated with all exogenous phytohormones, except zeatin riboside, leading to the hypothesis that callus induction competence was closely associated with endogenous ABA/IAA ratio. This first report should assist further genetic studies of this rare Lilium and other bulbous plants.