GH3::GUS reflects cell-specific developmental patterns and stress-induced changes in wood anatomy in the poplar stem
Thomas Teichmann (1, 2, 3), Waode Hamsinah Bolu-Arianto (1, 2), Andrea Olbrich (2), Rosemarie Langenfeld-Heyser (2), Cornelia Göbel (4), Peter Grzeganek (4), Ivo Feussner (4), Robert Hänsch (5) and Andrea Polle (2, 6)
1. These authors contributed equally to this work / 2. Institut für Forstbotanik, Büsgenweg 2, Georg-August-Universität Göttingen, 37077 Göttingen, Germany / 3. Present address: Abteilung Zellbiologie der Pflanze, Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Untere Karspüle
2, Georg-August-Universität Göttingen, 37073 Göttingen, Germany / 4. Abteilung Biochemie, Albrecht-von-Haller-Institut für Pflanzenwissenschaften, Justus-von-Liebig-Weg 11, Georg-August-Universität
Göttingen, 37077 Göttingen, Germany / 5. Institut für Pflanzenbiologie, Humboldtstrasse 1, Technische Universität Braunschweig, 38106 Braunschweig, Germany / Corresponding author () / Received December 21, 2007; accepted April 21, 2008; published online July 1, 2008
Summary
GH3 genes related to the auxin-inducible Glycine max (L.) Merr. GmGH3 gene encode enzymes that conjugate amino acids to auxin. To investigate the role of GH3 enzymes in stress responses and normal
wood development, Populus × canescens (Ait.) was transformed with the promoter-reporter construct GH3::GUS containing a GH3 promoter and the 5′ UTR from soybean.
β-Glucuronidase (GUS) activity was present in the vascular tissues of leaves and in developing lateral roots and was inducible
in silent tissues by external auxin application. A decrease in GUS activity from the stem apex to the bottom corresponded
to decreases in auxin concentrations in these tissues. High auxin concentration and high GH3::GUS activity were present in
the pith tissue, which may provide storage for auxin compounds. GH3 reporter was active in ray cells, paratracheal parenchyma
cells, maturing vessels and in cells surrounding maturing phloem fibers but not in the cambium and immature phloem, despite
high auxin concentrations in the latter tissues. However, the GH3 promoter in these tissues became active when the plants
were exposed to abiotic stresses, like bending or salinity, causing changes in wood anatomy. We suggest that adjustment of
the internal auxin balance in wood in response to environmental cues involves GH3 auxin conjugate synthases.
Keywords:
auxin, development, GH3, Populus, salt stress, tension wood, xylem.
