Xylella fastidiosa pil-chp operon is involved in regulating key structural genes of both type I and IV pili

Authors

  • Lingyun Hao Section of Plant Pathology and Plant-Microbe Biology, SIPS, Cornell University-New York State Agricultural Experiment Station, Geneva, NY, 14456, USA
  • D. Athinuwat Section of Plant Pathology and Plant-Microbe Biology, SIPS, Cornell University-New York State Agricultural Experiment Station, Geneva, NY, 14456, USA
  • K. Johnson Section of Plant Pathology and Plant-Microbe Biology, SIPS, Cornell University-New York State Agricultural Experiment Station, Geneva, NY, 14456, USA
  • L. Cursino Department of Biology, Hobart and William Smith Colleges, Geneva, NY, 14456, USA
  • T. J. Burr Section of Plant Pathology and Plant-Microbe Biology, SIPS, Cornell University-New York State Agricultural Experiment Station, Geneva, NY, 14456, USA
  • P. Mowery Department of Biology, Hobart and William Smith Colleges, Geneva, NY, 14456, USA

DOI:

https://doi.org/10.5073/vitis.2017.56.55-62

Keywords:

Xylella fastidiosa, pil-chp, Pierce's disease, PilG, PilJ, type I pili, type IV pili

Abstract

Xylella fastidiosa is the causal agent of Pierce's disease (PD) in grapevines. It has type I and type IV pili, which are both virulence factors involved in the PD-associated processes of motility, aggregation, and biofilm formation. Many questions remain as to how the two pili are regulated. We previously identified a X. fastidiosa pil-chp chemosensory-like cluster as an operon composed of genes pilG-I-J-L-chpB-C. In this study, we deleted pilG (resulting in a ∆pilG-I strain) and pilJ and discovered that both mutants (∆pilG-I and ∆pilJ) had reduced virulence after 24 weeks post-inoculation, whereas ∆chpB and ∆chpC did not. Both ∆pilG-I and ∆pilJ lost motility and were impaired in biofilm formation in rich artificial media and xylem sap. Gene expression was significantly downregulated for representative fimbrial adhesin and motility genes in ∆pilG-I, and to a lesser extent in ∆pilJ. Our data suggest that Pil, but not Chp, proteins are virulence factors, and pilG-I-J are involved in transcriptional regulation of type I and IV pili virulence genes and therefore motility and biofilm formation. To our knowledge, this is the first report of a chemotaxis-like operon involved in the regulation of key structural genes of both type I and type IV pili.


Author Biography

P. Mowery, Department of Biology, Hobart and William Smith Colleges, Geneva, NY, 14456, USA

Biology department

Associate professor

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Published

2017-04-21

Issue

Vol. 56 No. 2 (2017): Vitis

Section

Article

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