Embryo zeatin

Oligosaccharides (d.p. 4-8) prepared by hydrolysis of galacto-P(l-4)glucomannan were inhibitors at 10-4 to lOpM of hormonal stimulated elongation of pea stem segments, and also affected the viability of spruce embryos on media supplemented with indole-3-acetic acid zeatin [81]. 

The enzyme converting Z to DHZ, zeatin reductase, was characterised in Phaseolus vulgaris embryos [26]. The reduction proceeds only in the presence of NADPH and the enzyme is verj specific, with the highest affinity for Z (cZ, ZR, iPA, iPAR are not substrates, see also part 3.1.1. of this article). Taking into account that bases of isoprenoid cytokinins may represent the physiologically active forms of cytokinins [6], the conversion of Z to DHZ by zeatin reductase may prevent the loss of cytokinin activity caused by degradation of Z (but not that of DHZ, cf. part 3.1.5. of this article) by cytokinin oxidase. 

The enzyme zeatin reductase, responsible for the reduction of the side chain double bond in zeatin and subsequent formation of dihydrozeatin, was partially purified from Phaseolus vulgaris embryos and characterised [26]. As already mentioned in part 2.1. of... 

Genetic Differences in the Enzymatic Regulation of Zeatin Metabolism in Phaseobts Embryos... 

Ammirato P (1977) Hormonal control of somatic embryo development from cultured cells of caraway. Interactions of abscisic acid, zeatin, and gibberellic acid. Plant Physiol (Bethesda) 59 579-586... 

Transfer embryos to MS medium supplemented with 10 m tre Zeatin and 2-4 mg/litre PPT (use higher concentrations of PPT for more healthy-tooking material, this depends on the wheat variety used). 

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