Thaumatin-like proteins are differentially expressed and localized in phloem tissues of hybrid poplar
Date
2010-08-26
Authors
Dafoe, Nicole J.
Gowen, Brent E.
Constabel, C. Peter
Journal Title
Journal ISSN
Volume Title
Publisher
BioMed Central
Abstract
Background: Two thaumatin-like proteins (TLPs) were previously identified in phloem exudate of hybrid poplar
(Populus trichocarpa × P. deltoides) using proteomics methods, and their sieve element localization confirmed by
immunofluorescence. In the current study, we analyzed different tissues to further understand TLP expression and
localization in poplar, and used immunogold labelling to determine intracellular localization.
Results: Immunofluorescence using a TLP antiserum confirmed the presence of TLP in punctate, organelle-like
structures within sieve elements. On western blots, the antiserum labeled two constitutively expressed proteins
with distinct expression patterns. Immunogold labelling suggested that TLPs are associated with starch granules
and starch-containing plastids in sieve elements and phloem parenchyma cells. In addition, the antiserum
recognized TLPs in the inner cell wall and sieve plate region of sieve elements.
Conclusions: TLP localization in poplar cells and tissues is complex. TLP1 is expressed predominantly in tissues
with a prominent vascular system such as midveins, petioles and stems, whereas the second TLP is primarily
expressed in starch-storing plastids found in young leaves and the shoot apex.
Description
BioMed Central
Keywords
Centre for Forest Biology
Citation
Dafoe et al.: Thaumatin-like proteins are differentially expressed and localized in phloem tissues of hybrid poplar. BMC Plant Biology 2010 10:191.