This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Devescovi, G. Articles by Venturi, V. Search for Related Content PubMed PubMed Citation Articles by Devescovi, G. Articles by Venturi, V. Agricola Articles by Devescovi, G. Articles by Venturi, V.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, August 2007, p. 4950-4958, Vol. 73, No. 15
0099-2240/07/$08.00+0     doi:10.1128/AEM.00105-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

Involvement of a Quorum-Sensing-Regulated Lipase Secreted by a Clinical Isolate of Burkholderia glumae in Severe Disease Symptoms in Rice

Giulia Devescovi,¹ Joseph Bigirimana,² Giuliano Degrassi,¹ Laura Cabrio,² John J. LiPuma,⁴ Jinwoo Kim,³ Ingyu Hwang,³ and Vittorio Venturi^1,2*

Bacteriology Group, International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34012 Trieste, Italy,¹ Plant Bacteriology Group, International Centre for Genetic Engineering and Biotechnology, Biosafety Outstation, Via Piovega 23, 31050 Ca'Tron di Roncade, Treviso, Italy,² Department of Agricultural Biotechnology and Center for Agricultural Biomaterials, Seoul National University, Seoul 151-921, Korea,³ Department of Pediatrics and Communicable Diseases, University of Michigan Medical School, Ann Arbor, Michigan 48109⁴

Received 16 January 2007/ Accepted 30 May 2007

Burkholderia glumae is an emerging rice pathogen in several areas around the world. Closely related Burkholderia species are important opportunistic human pathogens for specific groups of patients, such as patients with cystic fibrosis and patients with chronic granulomatous disease. Here we report that the first clinical isolate of B. glumae, strain AU6208, has retained its capability to be very pathogenic to rice. As previously reported for rice isolate B. glumae BGR1 (and also for the clinical isolate AU6208), TofI or TofR acyl homoserine lactone (AHL) quorum sensing played a pivotal role in rice virulence. We report that AHL quorum sensing in B. glumae AU6208 regulates secreted LipA lipase and toxoflavin, the phytotoxin produced by B. glumae. B. glumae AU6208 lipA mutants were no longer pathogenic to rice, indicating that the lipase is an important virulence factor. It was also established that type strain B. glumae ATCC 33617 did not produce toxoflavin and lipase and was nonpathogenic to rice. It was determined that in strain ATCC 33617 the LuxR family quorum-sensing sensor/regulator TofR was inactive. Introducing the tofR gene of B. glumae AU6208 in strain ATCC 33617 restored its ability to produce toxoflavin and the LipA lipase. This study extends the role of AHL quorum sensing in rice pathogenicity through the regulation of a lipase which was demonstrated to be a virulence factor. It is the first report of a clinical B. glumae isolate retaining strong rice pathogenicity and finally determined that B. glumae can undergo phenotypic conversion through a spontaneous mutation in the tofR regulator.

---

* Corresponding author. Mailing address: Bacteriology Group, International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34012 Trieste, Italy. Phone: 39 040-3757317. Fax: 39 040-226555. E-mail: venturi{at}icgeb.org

Published ahead of print on 8 June 2007.

---

Applied and Environmental Microbiology, August 2007, p. 4950-4958, Vol. 73, No. 15
0099-2240/07/$08.00+0     doi:10.1128/AEM.00105-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Steindler, L., Bertani, I., De Sordi, L., Schwager, S., Eberl, L., Venturi, V. (2009). LasI/R and RhlI/R Quorum Sensing in a Strain of Pseudomonas aeruginosa Beneficial to Plants. Appl. Environ. Microbiol. 75: 5131-5140 [Abstract] [Full Text]  
• Suarez-Moreno, Z. R., Caballero-Mellado, J., Venturi, V. (2008). The new group of non-pathogenic plant-associated nitrogen-fixing Burkholderia spp. shares a conserved quorum-sensing system, which is tightly regulated by the RsaL repressor. Microbiology 154: 2048-2059 [Abstract] [Full Text]