Developmental and Structural Section
DeMason, Darleen , Polowick, Patricia .
DR5::GUS expression in pea (Pisum sativum).
The recent availability of the DR5::GUS reporter construct to visualize regions of auxin accumulation allows plant biologists opportunities to test old and new questions about the roles of auxin in developmental processes. DR5 is a synthetic auxin-responsive promoter that consists of a 7X repeat of the ARF site (AuxRE) from the soybean GH3 promoter and a 35S minimal promoter fused to the GUS-encoding reporter gene. In Arabidopsis, DR5::GUS is sensitive to auxin in a dosage dependent manner, and its activity reflects endogenous auxin levels in plant parts under the staining conditions typically used. We transformed pea (Pisum sativum) with DR5::GUS and several lines, from independent events, have shown stable expression through T5. In pea, GUS expression occurred in expected places: such as embryos, root tips, floral buds, procambium, pollen and trichomes. We have confirmed auxin regulation in root and shoot tips. For all strong auxins exogenously applied, blue staining was darker and more uniform than control roots and shoot tips. In sections of stained root primordia, blue color was present in the root cap, quiescent center, protoderm and protoxylem. In leaf primordia, dark blue staining occured in the distal tip of the leaf primordium from P1 through P4. Lateral tendril primordia and tendril tips stained more intensely blue and for more plastochrons than leaflet primordia and tips. Blue (GUS) staining in floral organs during initiation and development also revealed specific, shifting patterns. The DR5::GUS transgene is being crossed into various different mutant genotypes, which will allow us to identify the roles that auxin plays in different developmental events in pea.
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1 - University of California Riverside, Department of Botany & Plant Sciences, Riverside, California, 92521-0124, USA
2 - National Research Council Canada, Plant Biotechnology Institute, Saskatoon, SK, S7N 0W9
Presentation Type: Oral Paper:Papers for Sections
Location: PDR 2/Hilton
Date: Monday, July 9th, 2007
Time: 10:15 AM