Tree Genetics & Genomes

, Volume 8, Issue 1, pp 177–194

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


  • Xia Ye
    • College of HorticultureHenan Agricultural University
    • Department of Plant SciencesUniversity of Tennessee
  • Suhua Yuan
    • Department of Plant SciencesUniversity of Tennessee
    • Institute for Plant Genomics and BiotechnologyTexas A&M University
  • Hong Guo
    • Department of Biochemistry, Cellular and Molecular BiologyUniversity of Tennessee
  • Feng Chen
    • Department of Plant SciencesUniversity of Tennessee
    • Bioenergy Science CenterOak ridge National Laboratory
  • Gerald A. Tuskan
    • Environmental Science DivisionOak Ridge National Laboratory
    • Bioenergy Science CenterOak ridge National Laboratory
    • Department of Plant SciencesUniversity of Tennessee
    • Bioenergy Science CenterOak ridge National Laboratory
Original Paper

DOI: 10.1007/s11295-011-0431-1

Cite this article as:
Ye, X., Yuan, S., Guo, H. et al. Tree Genetics & Genomes (2012) 8: 177. doi:10.1007/s11295-011-0431-1


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.


Xyloglucan endotransglycosylase/hydrolases (XTHs) Gene duplications and divergence Gene expression Populus Arabidopsis



Xyloglucan endotransglycosylase


Xyloglucan hydrolase


Xyloglucan endotransglycosylase/hydrolases




Indole-3-acetic acid


Salicylic acid


Gibberellic acid




Jasmonic acid


Abscisic acid



Supplementary material

11295_2011_431_MOESM1_ESM.doc (1.6 mb)
ESM 1 The Ct data for each reaction of the XTH genes in Populus (DOC 1625 kb)
11295_2011_431_MOESM2_ESM.doc (42 kb)
ESM 2 The efficiency for each pair primers of the XTH genes in Populus (DOC 41 kb)
11295_2011_431_MOESM3_ESM.doc (38 kb)
ESM 3 The promoter sequences of paralogous genes (DOC 38 kb)
11295_2011_431_MOESM4_ESM.doc (52 kb)
ESM 4 The gene models of the PtXTH genes (DOC 51 kb)
11295_2011_431_MOESM5_ESM.doc (48 kb)
ESM 5 The gene structure analysis of the PtXTH genes (DOC 47 kb)

Copyright information

© Springer-Verlag 2011