| Abstract Detail
Hormone Biology Barkawi, Lana [1], Gardner, Gary [1], Cohen, Jerry D. [2]. Roles for Multiple Auxin Biosynthetic Pathways. Biochemical and genetic studies of higher plants have shown that the normal pathway for the production of indole-3-acetic acid (IAA) in seedlings is direct from indole by a tryptophan-independent pathway (TI). A tryptophan-dependent pathway (TD) has been shown to be operative, however, in the first hours after a wounding stress. It is unknown which TD pathway is activated by wounding or if the IAA produced following wounding has a discrete role from the IAA produced under normal growth conditions. We are testing whether the TD-IAA that is used for local growth at the site of a wound comes from the same metabolic source as the IAA that is transported by polar auxin transport (PAT) for normal growth and development. To examine these ideas, PAT studies have been done with maize coleoptile sections using agar donor (containing 3H-IAA) and receiver blocks. To minimize the effects of wounding, PAT experiments were also done on intact seedlings by microinjection at the apex. In these experiments, PAT was inhibited by 1-naphthylphthalamic acid (NPA). Stable isotope labeled tryptophan and anthranilate, precursors whose relative incorporation into IAA reveals which pathway is being favored, have been used in the donor blocks and at the apex of intact seedlings, and we have seen evidence of polar transport of both that is partially inhibited by NPA. We are using mass spectrometry in order to determine the labeling of IAA from each precursor to establish which pathway is being favored. We have found that in coleoptile sections PAT capacity drops steadily over time after wounding. It may be that callus cells that form at the cut end of the section do not transport IAA basipetally, perhaps as a mechanism to maintain high levels of IAA at the wound site. USDA-NRI 2005-35318-16197.
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1 - University of Minnesota, Horticultural Science
2 - University of Minnesota, Horticultural Science, 305 Alderman Hall, 1970 Folwell Avenue, Saint Paul, MN, 55108, USA
Keywords:
Auxin transport
Indole-3-acetic acid
Tryptophan
wounding
Anthranilate.
Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P35019
Abstract ID:347 |
