Location of transported auxin in etiolated maize shoots using 5-azidoindole-3-acetic acid. [Zea mays L]

Journal Article · Sun Jul 01 00:00:00 EDT 1990 · Plant Physiology; (USA)

DOI:https://doi.org/10.1104/pp.93.3.1154· OSTI ID:5957523

Jones, A M ^[1]

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1. Univ. of North Carolina, Chapel Hill (USA)

A study was undertaken using the photoaffinity labeling agent, tritiated 5-azidoindole-3-acetic acid (({sup 3}H),5-N{sub 3}IAA), to identify cells in the etiolated maize (Zea mays L.) shoot which transport auxin. Transport of ({sup 3}H),5-N{sub 3}IAA was shown to be polar, inhibited by 2,3,5-triiodobenzoic acid (TIBA) and essentially freely mobile. There was no detectable radiodecomposition of ({sup 3}H),5-N{sub 3}IAA within tissue kept in darkness for 4 hours. Shoot tissue which had taken up ({sup 3}H),5-N{sub 3}IAA was irradiated with ultraviolet light to covalently fix the photoaffinity labeling agent within cells that contained it at the time of photolysis. Subsequent microautoradiography showed that all cells contained radioactivity; however, the amount of radioactivity varied among different cell types. Epidermal cells contained the most radioactivity per area, approximately twofold more than other cells. Parenchyma cells in the mature stelar region contained the next largest amount and cortical cells, sieve tube cells, tracheary cells, and all cells in the leaf base contained the least amount of the radioactive label. Two observations suggest that the auxin within the epidermal cells is transported in a polar manner: (a) the amount of auxin in the epidermal cells is greatly reduced in the presence of TIBA, and (b) auxin accumulates on the apical side of a wound in the epidermis and is absent on the basal side. While these results indicate that auxin in the epidermis is polarly transported, this tissue cannot be the only pathway since the epidermis is only a small fraction of the shoot volume.

• OSTI ID: 5957523
• Journal Information: Plant Physiology; (USA), Vol. 93:3; ISSN 0032-0889
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
AUXINS
BIOCHEMICAL REACTION KINETICS
MAIZE
PHYSIOLOGY
AUTORADIOGRAPHY
PLANT CELLS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
ULTRAVIOLET RADIATION
CEREALS
ELECTROMAGNETIC RADIATION
GRASS
HYDROGEN COMPOUNDS
ISOTOPE APPLICATIONS
KINETICS
LILIOPSIDA
MAGNOLIOPHYTA
PLANT GROWTH REGULATORS
PLANTS
RADIATIONS
REACTION KINETICS
551001* - Physiological Systems- Tracer Techniques