Growth inhibition of the cereal root pathogens Rhizoctonia solani AG8, R. oryzae and Gaeumannomyces graminis var. tritici by a recombinant 42-kDa endochitinase from Trichoderma harzianum

Yongchun Wu, Diter Von Wettstein, C. Gamini Kannangara, Jayaveeramuthu Nirmala, R. James Cook

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11 Scopus citations

Abstract

The objective of this study was to determine the effectiveness of a 42-kDa endochitinase coded by the ThEn42 gene from Trichoderma harzianum as a potential source of transgenic resistance to Rhizoctonia root rot of barley caused by Rhizoctonia solani AG8 and/or R. oryzae . The gene cThEn42 was codon optimized (GC content increased from 53.3 to 65.1%) and then synthesized to produce the modified cThEn42GC in Pichia pastoris for in vitro tests. Two expression vectors were constructed: one with the fungal signal peptide and the fungal activation peptide [ FSP-FAP-cThEn(GC) ] and the other with barley chitinase 26 signal peptide followed by the fungal signal and activation peptides [ SP(HVChi26)-FSP-FAP-cThEn(GC) ]. N-terminal sequencing showed that, of two proteins secreted into liquid medium, FSP was cleaved off faithfully in one protein and both FSP and FAP were cleaved from the other protein. Purified endochitinase provided strong in vitro inhibition of both R. solani AG8 and R. oryzae . The enzyme had an intermediate inhibitory activity against Gaeumannomyces graminis var. tritici , and no inhibitory activity against Fusarium graminearum, F. pseudograminearum, and F. culmorum.

Original languageEnglish (US)
Pages (from-to)631-646
Number of pages16
JournalBiocontrol Science and Technology
Volume16
Issue number6
DOIs
StatePublished - Jun 1 2006

Bibliographical note

Funding Information:
We would like to thank Dr Norbert Wolf, Mr Rainer Stahl at Maltagen, Andernach, Germany, and Dr Henny Horvath for support with the synthesis of the endochitinase transgene. Financial support for this research was provided by the US Department of Agriculture, Agricultural Research Service, the Washington Barley Commission, the R.A. Nilan Distinguished Professorship and the R. J. Cook Endowed Chair in Wheat Research.

Keywords

  • Biological control
  • Endochitinase
  • Gaeumannomyces graminis
  • Pichia pastoris
  • R. oryzae
  • Rhizoctonia solani AG8
  • Soilborne plant pathogens
  • Trichoderma harzianum

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