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

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...

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Bibliographic Details
Published in:Planta 2002-02, Vol.214 (4), p.505-509
Main Authors: Ribnicky, David M., Cohen, Jerry D., Hu, Wei-Shou, Cooke, Todd J.
Format: Article
Language:English
Subjects:
Agronomy. Soil science and plant productions
Auxins
Biological and medical sciences
Biosynthesis
Carrots
Daucus carota - embryology
Daucus carota - growth & development
Daucus carota - metabolism
Economic plant physiology
Embryo development. Germination
Embryogenesis
Embryos
Fundamental and applied biological sciences. Psychology
Germination and dormancy
Growth and development
Indoleacetic Acids - biosynthesis
Indoleacetic Acids - metabolism
Ovaries
Ovules
Plant physiology and development
Plants
Reproduction - physiology
Seeds - growth & development
Seeds - metabolism
Somatic embryos
Totipotency
Tryptophan - metabolism
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Summary: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.
ISSN:0032-0935
1432-2048
DOI:10.1007/s004250100639