Nitrogen-dependent accumulation of cytokinins in root and the translocation to leaf: implication of cytokinin species that induces gene expression of maize response regulator

Plant Cell Physiol. 2001 Jan;42(1):85-93. doi: 10.1093/pcp/pce009.

Abstract

We have described the spatial and temporal accumulation pattern of various cytokinin species in roots, xylem sap and leaves during the resupply of nitrogen in maize. Upon addition of nitrate to nitrogen-depleted maize plants, isopentenyladenosine-5'-monophosphate (iPMP) started to accumulate in roots within 1 h preceding accumulation of trans-zeatin riboside-5'-monophosphate (ZMP), trans-zeatin riboside (ZR) and trans-zeatin (Z). In the xylem flow, both exudation rate of xylem sap and the concentration of the cytokinins increased, and ZR was the dominant species in the sap. In leaf tissue, the accumulation level of Z, which was the dominant form, started to increase 4 h after nitrate resupply to plants and the level was maintained for at least 24 h. Administration of a near physiological concentration of Z, ZR or ZMP (Z-type cytokinins) to detached leaves induced the accumulation of ZmRR1 transcript, that encode maize response regulators, but administration of isopentenyladenine, isopentenyladenosine or iPMP did not. These results strongly suggest that cytokinins are transported across the roots to shoots in response to nitrogen availability, and that, most probably, Z-type cytokinin(s), trigger the induction of ZmRR1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine / analogs & derivatives*
  • Adenosine / genetics
  • Adenosine / metabolism
  • Adenosine Monophosphate / analogs & derivatives*
  • Adenosine Monophosphate / metabolism
  • Aminoimidazole Carboxamide / analogs & derivatives*
  • Aminoimidazole Carboxamide / metabolism
  • Blotting, Northern
  • Chromatography, Liquid
  • Cytokinins / metabolism*
  • Enzyme-Linked Immunosorbent Assay
  • Gene Expression Regulation, Plant
  • In Vitro Techniques
  • Isopentenyladenosine / analogs & derivatives*
  • Isopentenyladenosine / genetics
  • Isopentenyladenosine / metabolism
  • Mass Spectrometry
  • Models, Biological
  • Nitrates / physiology*
  • Nitrogen / physiology
  • Plant Leaves / metabolism
  • Plant Roots / metabolism
  • Plant Stems / metabolism
  • Ribonucleotides / metabolism
  • Time Factors
  • Zea mays / genetics
  • Zea mays / metabolism*
  • Zeatin / metabolism

Substances

  • Cytokinins
  • Nitrates
  • Ribonucleotides
  • N(6)-(delta(2)-isopentenyl)adenosine 5'-monophosphate
  • Aminoimidazole Carboxamide
  • Adenosine Monophosphate
  • Isopentenyladenosine
  • Zeatin
  • zeatin riboside
  • AICA ribonucleotide
  • Adenosine
  • Nitrogen