Abstract
Xyloglucan endotransglycosylase/hydrolases (XTHs) are believed to modify the cell wall structure by cleaving a xyloglucan polymer and transferring the newly generated, potentially reducing, terminal to another xyloglucan. We report here the detailed analysis of 37 Populus trichocarpa XTH genes/proteins in their divergence in both the coding and 5′ promoter regions. Our results show that the Populus XTH genes have experienced whole-genome and local duplications and pre- and post-speciation divergence. Genome-wide and segmental duplications seem to be dominant in subfamily I and III, while tandem duplication seems to be the major mechanism for the subfamily II expansion, which also has higher average ratios of K a/K s compared to those in subfamily I and III. There was a general lack of organ-specific gene expression. In contrast, the expression patterns in subfamily II varied in response to various hormone treatments, with II-A being up-regulated and II-B down-regulated after 2 h of hormone treatment. Expression for this subfamily was verified using the 1. 5-kb PtXTH22 promoter that was fused with the GUS reporter gene and transformed into Arabidopsis. The PtXTH22 promoter contains auxin response element, ethylene insensitive 3-like factors, and brassinosteroid response cis-elements. Histochemical GUS staining of transgenic Arabidopsis seedlings confirmed that the PtXTH22 promoter was up-regulated by several hormones.
Original language | English |
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Pages (from-to) | 177-194 |
Number of pages | 18 |
Journal | Tree Genetics and Genomes |
Volume | 8 |
Issue number | 1 |
DOIs | |
State | Published - Feb 2012 |
Funding
Acknowledgments This research was supported in part by a Department of Energy-Bioenergy Center grant and by the Consortium for Plant Biotechnology Research, Inc. The BioEnergy Science Center is a US Department of Energy–Bioenergy Research Center supported by the Office of Biological and Environmental Research in the Department of Energy Office of Science.
Keywords
- Arabidopsis
- Gene duplications and divergence
- Gene expression
- Populus
- Xyloglucan endotransglycosylase/hydrolases (XTHs)