PLANT PHYSIOLOGY , Vol 109, Issue 4 1213-1217, Copyright © 1995 by American Society of Plant Biologists
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DEVELOPMENT AND GROWTH REGULATION |
Seed and 4-Chloroindole-3-Acetic Acid Regulation of Gibberellin Metabolism in Pea Pericarp
R. van Huizen, J. A. Ozga, D. M. Reinecke, B. Twitchin and L. N. Mander
Department of Agricultural, Food, and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada T6G 2P5 (R.v.H., J.A.O., D.M.R.)
In this study, we investigated seed and auxin regulation of gibberellin
(GA) biosynthesis in pea (Pisum sativum L.) pericarp tissue in situ,
specifically the conversion of [14C]GA19 to [14C]GA20. [14C]GA19 metabolism
was monitored in pericarp with seeds, deseeded pericarp, and deseeded
pericarp treated with 4-chloroindole-3-acetic acid (4-Cl-IAA). Pericarp
with seeds and deseeded pericarp treated with 4-Cl-IAA continued to convert
[14C]GA19 to [14C]GA20 throughout the incubation period (2-24 h). However,
seed removal resulted in minimal or no accumulation of [14C]GA20 in
pericarp tissue. [14C]GA29 was also identified as a product of [14C]GA19
metabolism in pea pericarp. The ratio of [14C]GA29 to [14C]GA20 was
significantly higher in deseeded pericarp (with or without exogenous
4-Cl-IAA) than in pericarp with seeds. Therefore, conversion of [14C]GA20
to [14C]GA29 may also be seed regulated in pea fruit. These data support
the hypothesis that the conversion of GA19 to GA20 in pea pericarp is seed
regulated and that the auxin 4-Cl-IAA can substitute for the seeds in the
stimulation of pericarp growth and the conversion of GA19 to GA20.