Srivastava, Avinash C. , Ayre, Brian G. .
Functional characterization of the AtSUC2 sucrose transporter from Arabidopsis thaliana in plant growth and development by tissue specific complementation assays.
The AtSUC2 is expressed throughout the phloem and is essential for sugar transport and growth, but its role in distributing sucrose to specific tissues is poorly understood. We aim to evaluate the role of AtSUC2 in sucrose distribution in specific organs, and to correlate these findings with transport efficiency through the whole plant. Arabidopsis lines heterozygous for an AtSUC2 null mutation were transformed with a complementing AtSUC2 cDNA fused to various tissue-specific promoters. The AtSUC2 promoter is active all along the phloem, and was used as a positive control. The rolC, and Commelina yellow mottle virus (CoYMV) promoters are also expressed throughout the phloem, but are subjected to different regulatory cascades. The GALACTINOL SYNTHASE (GAS) promoter is expressed only in the minor veins of the leaf and, the constitutive CaMV 35s promoter is expressed in all cell types. Growth was monitored in independent transformants segregating as homozygous knockout for the endogenous allele. AtSUC2 cDNA driven by AtSUC2, rolC and CoYMV promoters restored growth to near wild type levels, indicating that plants are tolerant of modest alterations in AtSUC2 expression. Plants expressing AtSUC2 from the GAS promoter had compromised growth but add robust seed set, indicating that AtSUC2 expression in large veins is not essential. Plants expressing AtSUC2 from the 35s promoter were severely debilitated, indicating that AtSUC2 expression outside the phloem is detrimental to whole-plant resource allocation. Radio-labeled sucrose is being used for high-resolution analysis of sugar transport in these plants.
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1 - University of North Texas, Biological Sciences, P O Box 305220, Denton, Texas, 76203-5220, USA
2 - University of North Texas, Biological Sciences, P O Box 305220, Denton, TX, 76203, USA
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM