Zeatin biosynthesis - Populus trichocarpa (black cottonwood)

Zeatin is a member of the cytokinin family, a class of phytohormones involved in various processes of growth and development in plants. Most abundant cytokinins are adenine-type, where the N6 position of adenine is substituted with an isoprenoid, such as in zeatin, or an aromatic side chain, such as in kinetin. Zeatin can be synthesized in two different pathways: the tRNA pathway and the AMP pathway. In the tRNA pathway zeatin is a recycled product of isopentenylated tRNAs. In the AMP pathway zeatin is synthesized from an isopentenyl donor, dimethylallyl diphosphate (DMAPP), and AMP, ADP, or ATP by isopentenyltransferases. After synthesis cytokinins can be glucosylated.

Metabolism; Metabolism of terpenoids and polyketides

Populus trichocarpa (black cottonwood) [GN:pop]

PMID:14726522

Kasahara H, Takei K, Ueda N, Hishiyama S, Yamaya T, Kamiya Y, Yamaguchi S, Sakakibara H.

Distinct isoprenoid origins of cis- and trans-zeatin biosyntheses in Arabidopsis.

J Biol Chem 279:14049-54 (2004)

PMID:11313355

Takei K, Sakakibara H, Sugiyama T.

Identification of genes encoding adenylate isopentenyltransferase, a cytokinin biosynthesis enzyme, in Arabidopsis thaliana.

J Biol Chem 276:26405-10 (2001)

PMID:11479373

Kakimoto T.

Identification of plant cytokinin biosynthetic enzymes as dimethylallyl diphosphate:ATP/ADP isopentenyltransferases.

Plant Cell Physiol 42:677-85 (2001)

PMID:15280363

Takei K, Yamaya T, Sakakibara H.

Arabidopsis CYP735A1 and CYP735A2 encode cytokinin hydroxylases that catalyze the biosynthesis of trans-Zeatin.

J Biol Chem 279:41866-72 (2004)

PMID:15342621

Hou B, Lim EK, Higgins GS, Bowles DJ.

N-glucosylation of cytokinins by glycosyltransferases of Arabidopsis thaliana.

J Biol Chem 279:47822-32 (2004)

PMID:9874810

Martin RC, Mok MC, Mok DW

Isolation of a cytokinin gene, ZOG1, encoding zeatin O-glucosyltransferase from Phaseolus lunatus.

Proc Natl Acad Sci U S A 96:284-9 (1999)

PMID:10364407

Martin RC, Mok MC, Mok DW

A gene encoding the cytokinin enzyme zeatin O-xylosyltransferase of Phaseolus vulgaris.

Plant Physiol 120:553-8 (1999)

PMID:12644686

Veach YK, Martin RC, Mok DW, Malbeck J, Vankova R, Mok MC

O-glucosylation of cis-zeatin in maize. Characterization of genes, enzymes, and endogenous cytokinins.

Plant Physiol 131:1374-80 (2003)

PMID:14555694

Werner T, Motyka V, Laucou V, Smets R, Van Onckelen H, Schmulling T

Cytokinin-deficient transgenic Arabidopsis plants show multiple developmental alterations indicating opposite functions of cytokinins in the regulation of shoot and root meristem activity.

Plant Cell 15:2532-50 (2003)

PMID:17062755

Miyawaki K, Tarkowski P, Matsumoto-Kitano M, Kato T, Sato S, Tarkowska D, Tabata S, Sandberg G, Kakimoto T

Roles of Arabidopsis ATP/ADP isopentenyltransferases and tRNA isopentenyltransferases in cytokinin biosynthesis.

Proc Natl Acad Sci U S A 103:16598-603 (2006)