Regulation of cytokinin biosynthesis, compartmentalization and translocation
Naoya Hirose,Kentaro Takei,Takeshi Kuroha,Tomoe Kamada-Nobusada,Hiroaki Hayashi,Hitoshi Sakakibara +5 more
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TL;DR: Biochemical and transgenic data suggest that AtENT6, an Arabidopsis ENT, could also participate in cytokinin nucleoside transport with a preference for iP riboside in vascular tissue and the compartmentalization of tZ- and iP-type cytokinins implies the involvement of a selective transport system.
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Abstract: Cytokinins, a group of mobile phytohormones, play an important role in plant growth and development, and their activity is finely controlled by environmental factors in the control of morphogenic and metabolic adaptations. Inorganic nitrogen sources, such as nitrate, are a major factor regulating gene expression of adenosine phosphate-isopentenyltransferase (IPT), a key enzyme of cytokinin biosynthesis. Modulation of IPT and macronutrient transporter gene expression in response to nitrate, sulphate and phosphate, and cytokinin-dependent repression of the transporter genes suggest that cytokinins play a critical role in balancing acquisition and distribution of macronutrients. Biased distribution of trans-zeatin (tZ)-type cytokinins in xylem and N 6 -(D 2 -isopentenyl)adenine (iP)-type cytokinins in phloem saps suggest that, in addition to acting as local signals, cytokinins communicate acropetal and systemic long-distance signals, and that structural side chain variations mediate different biological messages. The compartmentalization of tZ- and iP-type cytokinins implies the involvement of a selective transport system. Recent studies have raised the possibility of subsets of the purine permease family as a transporter of cytokinin nucleobases and equilibrative nucleoside transporters (ENT) for cytokinin nucleosides. These biochemical and transgenic data suggest that AtENT6, an Arabidopsis ENT, could also participate in cytokinin nucleoside transport with a preference for iP riboside in vascular tissue.
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References
Cytokinin Oxidase Regulates Rice Grain Production
Motoyuki Ashikari,Hitoshi Sakakibara,Shaoyang Lin,Toshio Yamamoto,Tomonori Takashi,Asuka Nishimura,Enrique R. Angeles,Qian Qian,Hidemi Kitano,Makoto Matsuoka +9 more
TL;DR: It is shown that a QTL that increases grain productivity in rice, Gn1a, is a gene for cytokinin oxidase/dehydrogenase (OsCKX2), an enzyme that degrades the phytohormone cytokinIn.
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Cytokinin-Deficient Transgenic Arabidopsis Plants Show Multiple Developmental Alterations Indicating Opposite Functions of Cytokinins in the Regulation of Shoot and Root Meristem Activity
TL;DR: The results are consistent with the hypothesis that cytokinins have central, but opposite, regulatory functions in root and shoot meristems and indicate that a fine-tuned control of catabolism plays an important role in ensuring the proper regulation of cytokinin functions.
1.5K
CYTOKININS: Activity, Biosynthesis, and Translocation
TL;DR: Recent findings on the relationship between CK structural variation and activity, distinct features in CK biosynthesis between higher plants and Agrobacterium infected plants, CK translocation at whole-plant and cellular levels, and CKs as signaling molecules for nutrient status via root-shoot communication are summarized.
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Cytokinin metabolism and action
David W. S. Mok,Machteld C. Mok +1 more
- 28 Nov 2003
TL;DR: This review centers on cytokinin metabolism with connecting discussions on biosynthesis and signal transduction, and important findings are summarized with emphasis on metabolic enzymes and genes.
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Inhibition of Leaf Senescence by Autoregulated Production of Cytokinin
Susheng Gan,Richard M. Amasino +1 more
TL;DR: This result demonstrates that endogenously produced cytokinin can regulate senescence and provides a system to specifically manipulate the senescences program.
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