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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.


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Journal ArticleDOI
TL;DR: The results emphasized the importance of the cell number per fruit at anthesis as a determining factor of final fruit size in tomatoes.
Abstract: Tomato fruit growth parameters, cell number and cell size, and hormone levels [IAA, abscisic acid (ABA), zeatin (Z)/zeatin riboside (ZR), isopentenyladenosine (i-Ado)/isopentenlyadenine (i-Ade)], in the wild-type (Lycopersicon pimpinellifolium Mill.) and a semi-isogenic mutant (mutant III) differing in fruit size were investigated during fruit development. An image-processing system was used for the determination of cell number and single cell size per fruit and hormone levels were measured by radioimmuno-assay (RIA). The bigger fruits of mutant III showed higher cell numbers throughout fruit development and cells enlarged faster than in wild-type fruits. During the first 10 days of fruit growth, the main cell division period after fertilization, high concentrations of cytokinins were found, these being correlated with high cell division activity. There were only slight differences in IAA and ABA levels in the different sized fruits. The results emphasized the importance of the cell number per fruit at anthesis as a determining factor of final fruit size in tomatoes. A possible relationship between cytokinins and subsequent fruit development is discussed.

134 citations

Journal ArticleDOI
TL;DR: The discovery of a cis-zeatin-specific O-glucosyltransferase isolated from maize indicates the existence of cis-specific regulatory elements in plants and suggests that cis-ZEatin and derivatives may be more important in cytokinin homeostasis than currently recognized.
Abstract: Zeatin is a naturally occurring cytokinin. Biosynthesis and metabolism studies of zeatin have been directed mostly at the trans isomer, although cis-zeatin and its riboside occur as major components in some plant species. It is not known whether parallel regulatory pathways exist for the two isomers. Based on the sequence of the gene ZOG1 encoding a trans-zeatin O-glucosyltransferase from Phaseolus (EC 2.4.1.203), a cis-zeatin-specific O-glucosyltransferase was isolated from maize. This gene, cisZOG1, contains an ORF of 1,401 nucleotides encoding a protein of 51.1 kDa with 41% identity to the Phaseolus ZOG1 protein. Unexpectedly, the maize enzyme recognizes as substrates cis-zeatin and UDP-glucose but not cis-ribosylzeatin, trans-zeatin, or trans-ribosylzeatin. This finding indicates the existence of cis-specific regulatory elements in plants and suggests that cis-zeatin and derivatives may be more important in cytokinin homeostasis than currently recognized.

134 citations

Journal ArticleDOI
TL;DR: Genotypic variation in leaf senescence may result from the difference in root characteristics, particularly in Z+ZR, iP+iPA, and ABA which are regulated by the root system directly or indirectly.
Abstract: Leaf senescence varies greatly among cotton cultivars, possibly due to their root characteristics, particularly the root-sourced cytokinins and abscisic acid (ABA). Early-senescence (K1) and late-senescence (K2) lines, were reciprocally or self-grafted to examine the effects of rootstock on leaf senescence and endogenous hormones in both leaves and xylem sap. The results indicate that the graft of K1 scion onto K2 rootstock (K1/K2) alleviated leaf senescence with enhanced photosynthetic (Pn) rate, increased levels of chlorophyll (Chl) and total soluble protein (TSP), concurrently with reduced malondialdehyde (MDA) contents in the fourth leaf on the main-stem. The graft of K2 scion onto K1 rootstock enhanced leaf senescence with reduced Pn, Chl, and TSP, and increased MDA, compared with their respective self-grafted control plants (K1/K1 and K2/K2). Reciprocally grafted plants differed significantly from their self-grafted control plants in levels of zeatin and its riboside (Z+ZR), isopentenyl and its adenine (iP+iPA), and ABA, but not in those of dihydrozeatin and its riboside (DHZ+DHZR) in leaves in late season, which was consistent with variations in leaf senescence between reciprocally and self-grafted plants. The results suggest that leaf senescence is closely associated with reduced accumulation of Z+ZR, and iP+iPA rather than DHZ+DHZR, or enhanced ABA in leaves of cotton. Genotypic variation in leaf senescence may result from the difference in root characteristics, particularly in Z+ZR, iP+iPA, and ABA which are regulated by the root system directly or indirectly.

134 citations

Journal Article
TL;DR: The differences in cytokinin oxidase activity between kernels which are maturing normally and those which will abort was so pronounced that cytokinIn oxidase levels can be considered an indicator of normal kernel development.

134 citations

Journal ArticleDOI
TL;DR: Regulation of maturation would facilitate future efforts to manipulate somatic embryos for large scale propagation in batch cultures, mechanized planting, artificial induction of dormancy, and incorporation into artificial seeds.
Abstract: The ability to control plant somatic embryogenesis is a necessary prelude to its development as an efficient biotechnological tool. The influence of different suspension culture techniques on the maturation of caraway (Carum carvi) somatic embryos and the effect of growth hormones in controlling development were studied. The three types of culture vessels (tumble tubes, test tubes, and Erlenmeyer flasks), each providing contrasting techniques of agitation, generated populations differing significantly in the frequencies of normal and abnormal embryos. Abscisic acid (ABA), at the appropriate concentrations, effectively normalized development in all systems, inhibiting abnormal proliferations and precocious germination and fostering normal maturation. For those cultures where embryos failed to develop on unsupplemented medium, zeatin in combination with ABA fostered growth and normal maturation. Carrot (Daucus carota) somatic embryo development could be similarly controlled. Such regulation of maturation would facilitate future efforts to manipulate somatic embryos for large scale propagation in batch cultures, mechanized planting, artificial induction of dormancy, and incorporation into artificial seeds.

133 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202333
2022103
202135
202034
201932
201848