TY - JOUR
T1 - Expression of a Trichoderma reesei β-1,4 endo-xylanase in tall fescue modifies cell wall structure and digestibility and elicits pathogen defence responses
AU - Buanafina, Marcia M.de O.
AU - Langdon, Tim
AU - Dalton, Sue
AU - Morris, Phillip
N1 - Funding Information:
Acknowledgments Authors would like to thank Dr. Kathy Brown (Penn State University) for giving access to the gas chromatography equipment and Barbara Hauck and Emma Timms-Taravella (IBERS/ Aberystwyth/UK) for technical assistance. This work was supported by the Biotechnology and Biological Sciences Research Council (BBSRC) and Genencor Inc. and by the National Research Initiative or Agriculture and Food Research Initiative Competitive Grants Program, [Grant No. 2008-02863] from the USDA National Institute of Food and Agriculture.
PY - 2012/12
Y1 - 2012/12
N2 - An endo-xylanase from Trichoderma reesei (xyn2) has been expressed in tall fescue targeted to the vacuole, apoplast or Golgi, constitutively under the control of the rice actin promoter, and to the apoplast under the control of a senescence enhanced gene promoter. Constitutive xylanase expression in the vacuole, apoplast, and golgi, resulted in only a small number of plants with low enzyme activities and in reduced plant growth in apoplast, and golgi targeted plants. Constitutive expression in the apoplast also resulted in increased levels of cell wall bound hydroxycinnamic acid monomers and dimers, but no significant effect on cell wall xylose or arabinose content. In situ constitutive xylanase expression in the Golgi also resulted in increased ferulate dimers. However, senescence induced xylanase expression in the apoplast was considerably higher and did not affect plant growth or the level of monomeric hydroxycinnamic acids or lignin in the cell walls. These plants also showed increased levels of ferulate dimers, and decreased levels of xylose with increased levels of arabinose in their cell walls. While the release of cell wall hydroxycinnamic acids on self digestion was enhanced in these plants in the presence of exogenously applied ferulic acid esterase, changes in cell wall composition resulted in decreases in both tissue digestibility and cellulase mediated sugar release. In situ detection of H2O2 production mediated by ethylene release in leaves of plants expressing apoplast xylanase could be leading to increased dimerisation. High-level xylanase expression in the apoplast also resulted in necrotic lesions on the leaves. Together these results indicate that xylanase expression in tall fescue may be triggering plant defence responses analogous to foliar pathogen attack mediated by ethylene and H2O2.
AB - An endo-xylanase from Trichoderma reesei (xyn2) has been expressed in tall fescue targeted to the vacuole, apoplast or Golgi, constitutively under the control of the rice actin promoter, and to the apoplast under the control of a senescence enhanced gene promoter. Constitutive xylanase expression in the vacuole, apoplast, and golgi, resulted in only a small number of plants with low enzyme activities and in reduced plant growth in apoplast, and golgi targeted plants. Constitutive expression in the apoplast also resulted in increased levels of cell wall bound hydroxycinnamic acid monomers and dimers, but no significant effect on cell wall xylose or arabinose content. In situ constitutive xylanase expression in the Golgi also resulted in increased ferulate dimers. However, senescence induced xylanase expression in the apoplast was considerably higher and did not affect plant growth or the level of monomeric hydroxycinnamic acids or lignin in the cell walls. These plants also showed increased levels of ferulate dimers, and decreased levels of xylose with increased levels of arabinose in their cell walls. While the release of cell wall hydroxycinnamic acids on self digestion was enhanced in these plants in the presence of exogenously applied ferulic acid esterase, changes in cell wall composition resulted in decreases in both tissue digestibility and cellulase mediated sugar release. In situ detection of H2O2 production mediated by ethylene release in leaves of plants expressing apoplast xylanase could be leading to increased dimerisation. High-level xylanase expression in the apoplast also resulted in necrotic lesions on the leaves. Together these results indicate that xylanase expression in tall fescue may be triggering plant defence responses analogous to foliar pathogen attack mediated by ethylene and H2O2.
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U2 - 10.1007/s00425-012-1724-9
DO - 10.1007/s00425-012-1724-9
M3 - Article
C2 - 22878642
AN - SCOPUS:84869492874
SN - 0032-0935
VL - 236
SP - 1757
EP - 1774
JO - Planta
JF - Planta
IS - 6
ER -