Evolution and divergence in the coding and promoter regions of the Populus gene family encoding xyloglucan endotransglycosylase/hydrolases

Xia Ye, Suhua Yuan, Hong Guo, Feng Chen, Gerald A. Tuskan, Zong Ming Cheng

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

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 languageEnglish
Pages (from-to)177-194
Number of pages18
JournalTree Genetics and Genomes
Volume8
Issue number1
DOIs
StatePublished - 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)

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