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Planta

, Volume 214, Issue 4, pp 505–509 | Cite as

An auxin surge following fertilization in carrots: a mechanism for regulating plant totipotency

  • David M. Ribnicky
  • Jerry D. Cohen
  • Wei-Shou Hu
  • Todd J. Cooke
Original Article

Abstract.

All plants exhibit the property of cellular totipotency, whereby individual cells can regenerate into an entire organism. However little is known about the underlying mechanisms regulating totipotency. Using a preparative microtechnique, we report an 80-fold surge in the concentration of free auxin that is correlated with the initial stages of zygotic embryogenesis in carrots. The concentration of free IAA increases from a basal level of ca. 25 ng/g FW in unfertilized ovules to ca. 2,000 ng/g FW in the late globular and early heart stages, then back to the basal level in the torpedo stage. This initial increase in IAA levels is diagnostic of the activity of the tryptophan-mediated pathway for IAA biosynthesis, while the maintenance of the basal levels is attributed to the tryptophan-independent pathway for IAA biosynthesis. Our observations are consistent with the hypothesis that the sequential activation of alternative IAA biosynthetic pathways is a critical mechanism for regulating carrot (Daucus carota L. cv. Danvers 126) embryogenesis and other instances of plant totipotency.

Daucus (totipotency) Embryogenesis Indole-3-acetic acid (totipotency) Phytohormone analysis Reproduction (carrot) Totipotency 

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Copyright information

© Springer-Verlag 2001

Authors and Affiliations

  • David M. Ribnicky
    • 2
  • Jerry D. Cohen
    • 1
  • Wei-Shou Hu
    • 3
  • Todd J. Cooke
    • 2
  1. 1.Department of Horticultural Science, University of Minnesota, Saint Paul, MN 55108, USA
  2. 2.Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
  3. 3.Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, USA

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