The effects of five cytokinin antagonists on the growth
of cytokinin-autonomous lines of Phaseolus lunatus cv.
Kingston, Phaseolus vulgaris cv. Great Northern, and
Nicotiana tabacum cv. Wisconsin 38 callus tissues have been
compared. The antagonists tested included four N⁴-substituted 4-amino-2-methylthiopyrrolo[2,3-d]pyrimidines
bearing the following N⁴ side chains, 4-n-pentyl-
(ms²pnN⁴Prp), 4-n-hexyl- (ms²HxN⁴Prp),...
An enzyme catalyzing the formation of
O-glucosylzeatin in immature embryos of P. lunatus was
purified 2500 fold using ammonium sulfate precipitation
followed by affinity and anion exchange chromatography.
The enzyme uses trans-zeatin as substrate (Km 28 uM) but
not cis-zeatin. ribosylzeatin, or dihydrozeatin. Both
UDP-glucose and UDP-xylose can serve as...
Cytokinin oxidase activity in callus tissues of
Phaseolus vulgaris L. cv. Great Northern has been examined
using an assay based on the oxidation of radioactively
labeled N⁶ -(Δ² -isopentenyl) adenine (i⁶Ade) to adenine
(Ade). Conditions for the quantitative extraction and
assay of the enzyme have been established. The substrate
specificity...
1-Phenyl-3-(2-Thiazoly1)-2-Thiourea (PTTU), has been reported to
inhibit dopamine-fi-hydroxylase (a copper-containing enzyme involved in
the pathway of biosynthesis of adrenaline in animal systems). In the
present study, PTTU has been shown to have cytokinin activity in the
tobacco bioassay. The cytokinin activity of PTTU suggested that
cytokinin-active N⁶-substituted adenine derivatives might...
Cytokinins are a group of plant hormones mediating cell division and
differentiation. Zeatin is a naturally occurring and highly active cytokinin that is rapidly
metabolized in Phaseolus seeds. The metabolites and enzymes mediating the conversion
have been studied extensively. Zeatin metabolic enzymes may be utilized in studying the
regulation of...
A critical balance of hormones is necessary for normal plant
development. Therefore, precise mechanisms must exist to maintain
proper levels of cytokinins, a group of hormones regulating cell
division and differentiation. Structural modifications of the naturally
occurring cytokinin, zeatin; including the oxidation, O-glycosylation
and reduction of the N⁶-side chain; may...
Cytokinins are plant hormones regulating cell division and differentiation.
Most developmental events from germination, vegetative morphogenesis to seed
and fruit set are influenced by cytokinins. t,ns-Zeatin is the major natural
occurring cytokinin. Its isomer, cis-zeatin, and its derivatives are usually present in
low quantities and have traditionally been considered as...
Endogenous concentrations of indole-3-acetic acid (IAA) and cytokinins were compared to the tendency for plagiogravitropjc growth in rooted stein cuttings of Douglas-fir. A chromatographic method was developed for
the purification and quantitation of trace levels of IAA. Two elutions with reverse-phase high performance liquid
chromatography (HPLC) using a fluorescence detector...
The phytohormones auxin and cytokinin control plant development through a complex network of interactions which include synergistic, additive, and opposite effects whose mechanisms are unknown. The auxin-insensitive diageotropica (dgt) mutant provided a tool to dissect the relationship between auxin- and cytokinin-induced responses in tomato. Morphological, physiological, and molecular data support...
