Two genes encoding GH10 xylanases are essential for the virulence of the oomycete plant pathogen Phytophthora parasitica
- 222 Downloads
Plant cell walls are pivotal battlegrounds between microbial pathogens and their hosts. To penetrate the cell wall and thereby to facilitate infection, microbial pathogens are equipped with a wide array of cell wall-degrading enzymes to depolymerize the polysaccharides in the cell wall. However, many of these enzymes and their role in the pathogenesis of microbial pathogens are not characterized, especially those from Oomycetes. In this study, we analyzed the function of four putative endo-beta-1,4-xylanase-encoding genes (ppxyn1–ppxyn4) from Phytophthora parasitica, an oomycete plant pathogen known to cause severe disease in a wide variety of plant species. All four genes belong to the glycoside hydrolase family 10 (GH10). Recombinant proteins of ppxyn1, ppxyn2, and ppxyn4 obtained from the yeast Pichia pastoris showed degrading activities toward birch wood xylan, but they behaved differently in terms of the conditions for optimal activity, thermostability, and durability. Quantitative RT-PCR revealed upregulated expression of all four genes, especially ppxyn1 and ppxyn2, during plant infection. In contrast, ppxyn3 was highly expressed in cysts and its close homolog, ppxyn4, in germinating cysts. To uncover the role of ppxyn1 and ppxyn2 in the pathogenesis of P. parasitica, we generated silencing transformants for these two genes by double-stranded RNA-mediated gene silencing. Silencing ppxyn1 and ppxyn2 reduced the virulence of P. parasitica toward tobacco (Nicotiana benthamiana) and tomato plants. These results demonstrate the crucial role of xylanase-encoding ppxyn1 and ppxyn2 in the infection process of P. parasitica.
KeywordsCell wall degrading enzyme GH10 Phytophthora Virulence Xylanase
We are grateful to Dr. Y. C. Wang (Department of Plant Pathology, Nanjing Agricultural University) for providing the plasmid vectors and technical assistance. This work was supported by the Ministry of Science and Technology, Taiwan.
- Blackman LM, Cullerne DP, Torreña P, Taylor J, Hardham AR (2015) RNA-Seq analysis of the expression of genes encoding cell wall degrading enzymes during infection of lupin (Lupinus angustifolius) by Phytophthora parasitica. PLoS One 10:e0136899. https://doi.org/10.1371/journal.pone.0136899 CrossRefPubMedPubMedCentralGoogle Scholar
- Chaparro-Garcia A, Wilkinson RC, Gimenez-Ibanez S, Findlay K, Coffey MD, Zipfel C et al (2011) The receptor-like kinase SERK3/BAK1 is required for basal resistance against the late blight pathogen Phytophthora infestans in Nicotiana benthamiana. PLoS One 6:e16608. https://doi.org/10.1371/journal.pone.0016608 CrossRefPubMedPubMedCentralGoogle Scholar
- Erwin DC, Ribeiro OK (1996) Phytophthora diseases worldwide. APS Press, St PaulGoogle Scholar
- Furman-Matarasso N, Cohen E, Du Q, Chejanovsky N, Hanania U, Avni A (1999) A point mutation in the ethylene-inducing xylanase elicitor inhibits the beta-1-4-endoxylanase activity but not the elicitation activity. Plant Physiol 121:345–351. https://doi.org/10.1104/pp.121.2.345 CrossRefPubMedPubMedCentralGoogle Scholar
- Judelson HS, Ah-Fong AMV, Aux G, Avrova AO, Bruce C, Cakir C et al (2008) Gene expression profiling during asexual development of the late blight pathogen Phytophthora infestans reveals a highly dynamic transcriptome. Mol Plant Microbe Interact 21:433–447. https://doi.org/10.1094/MPMI-21-4-0433 CrossRefPubMedGoogle Scholar
- Kubicek CP, Starr TL, Glass NL (2014) Plant cell wall–degrading enzymes and their secretion in plant-pathogenic fungi. Annu Rev Phytopathol 52:427–451. https://doi.org/10.1146/annurev-phyto-102313-045831 CrossRefPubMedGoogle Scholar
- Palm-Forster MAT, Eschen-Lippold L, Uhrig J, Scheel D, Lee J (2017) A novel family of proline/serine-rich proteins, which are phospho-targets of stress-related mitogen-activated protein kinases, differentially regulates growth and pathogen defense in Arabidopsis thaliana. Plant Mol Biol 95:123–140. https://doi.org/10.1007/s11103-017-0641-5 CrossRefPubMedPubMedCentralGoogle Scholar
- Soanes D, Richards TA (2014) Horizontal gene transfer in eukaryotic plant pathogens. Annu Rev Phytopathol 52:583–614. https://doi.org/10.1146/annurev-phyto-102313-050127 CrossRefPubMedGoogle Scholar
- Wu SC, Halley JE, Luttig C, Fernekes LM, Gutiérrez-Sanchez G, Darvill AG et al (2006) Identification of an endo-beta-1,4-d-xylanase from Magnaporthe grisea by gene knockout analysis, purification, and heterologous expression. Appl Environ Microbiol 72:986–993. https://doi.org/10.1128/AEM.72.2.986-993.2006 CrossRefPubMedPubMedCentralGoogle Scholar