title: Novel cytokinins: The predominant forms in mature buds of Pinus radiata.
abstract: To elicit the roles of cytokinins in the regulation of maturation of Pinus radiata D. Don, the spectrum of endogenous cytokinins and their concentration in the mature buds were analysed using double-solvent extraction, column complex purification and separation, a novel immunoaffinity purification method, normal and reverse phase high-pressure liquid chromatography, enzymatic treatment, radioimmunoassay and electrospray MS/MS spectrometry. We have isolated two novel cytokinin glycosides whose proposed structures are isopentenyladenine-9-(glucopyranosyl riboside), dihydrozeatin-9-(glucopyranosyl riboside) and confirmed the presence of zeatin-9-(glucopyranosyl riboside). We have also found the presence of novel phosphorylated forms of these 3 cytokinin ribosyl-linked glycosides. Quantitative analyses revealed that the cytokinin ribosyl-linked glycosides predominate in P. radiata mature buds. Although cytokinin free base, riboside and nucleotide forms are also present, we could find no evidence of the traditional cytokinin O- or N-glucosides in the conifer buds. Thus, cytokinin metabolism in mature buds of P. radiata is very different from other species previously examined.
authors.affiliation: Institute of Molecular BioSciences, College of Sciences, Massey University, Private Bag 11 222, Palmerston North, New Zealand; Forest Research, Private Bag 3020, Sala Street, Rotorua, New Zealand; Ministry of Research, Science and Technology, PO Box 5336, Wellington, New Zealand; Plant Health and Development, The Horticulture and Food Research Institute of New Zealand, Private Bag 11 030, Palmerston North, New Zealand.
authors.forename: Huaibi
authors.initials: H
authors.lastname: Zhang
authors.forename: Kathryn Joan
authors.initials: KJ
authors.lastname: Horgan
authors.forename: Paul Hugh
authors.initials: PH
authors.lastname: Stewart Reynolds
authors.forename: Gill Erna
authors.initials: GE
authors.lastname: Norris
authors.forename: Paula Elizabeth
authors.initials: PE
authors.lastname: Jameson