Abstract
A number of plant pathogenic fungi belonging to the genus Rhizopus are infamous for causing rice seedling blight. This plant disease is typically initiated by an abnormal swelling of the seedling roots without any sign of infection by the pathogen1,2,3,4. This characteristic symptom is in fact caused by the macrocyclic polyketide metabolite rhizoxin that has been isolated from cultures of Rhizopus sp.5,6. The phytotoxin exerts its destructive effect by binding to rice β-tubulin, which results in inhibition of mitosis and cell cycle arrest7,8. Owing to its remarkably strong antimitotic activity in most eukaryotic cells, including various human cancer cell lines, rhizoxin has attracted considerable interest as a potential antitumour drug9,10. Here we show that rhizoxin is not biosynthesized by the fungus itself, but by endosymbiotic, that is, intracellular living, bacteria of the genus Burkholderia. Our unexpected findings unveil a remarkably complex symbiotic-pathogenic relationship that extends the fungus–plant interaction to a third, bacterial, key-player, and opens new perspectives for pest control.
This is a preview of subscription content, access via your institution
Access options
Subscribe to this journal
Receive 51 print issues and online access
$199.00 per year
only $3.90 per issue
Buy this article
- Purchase on Springer Link
- Instant access to full article PDF
Prices may be subject to local taxes which are calculated during checkout
Similar content being viewed by others
References
Furuya, S., Kurata, M. & Saito, T. Studies on Rhizopus sp. causing growth injury of young rice seedlings and its chemical control. Proc. Assoc. Plant Protect. Shikoku 9, 49–55 (1974)
Ibaragi, T. Studies on rice seedling blight. I. Growth injury caused by Rhizopus sp. under high temperature. Ann. Phytopathol. Soc. Jpn 39, 141–144 (1973)
Gho, N., Sato, Z., Yaoita, T. & Aoyagi, K. Studies on the control of Rhizopus in the nursery cases of rice seedlings. 5. Influence of a phytotoxic substance produced by Rhizopus on growth of rice. Proc. Assoc. Plant Protect. Shikoku 26, 90–94 (1978)
Noda, T., Hashiba, T. & Sato, Z. The structural changes in young swollen roots of rice seedlings infected with Rhizopus chinensis Saito. Ann. Phytopathol. Soc. Jpn 46, 40–45 (1980)
Iwasaki, S. et al. Studies on macrocyclic lactone antibiotics. VII. Structure of a phytotoxin “rhizoxin” produced by Rhizopus chinensis. J. Antibiot. 37, 354–362 (1984)
Iwasaki, S. et al. Studies on macrocyclic lactone antibiotics. VIII. Absolute structures of rhizoxin and a related compound. J. Antibiot. 39, 424–429 (1986)
Koga-Ban, Y., Niki, T., Nagamura, Y., Sasaki, T. & Minobe, Y. cDNA sequences of three kinds of beta-tubulins from rice. DNA Res. 2, 21–26 (1995)
Takahashi, M. et al. Studies on macrocyclic lactone antibiotics. XI. Anti-mitotic and anti-tubulin activity of new antitumor antibiotics, rhizoxin and its homologues. J. Antibiot. 40, 66–72 (1987)
Tsuruo, T. et al. Rhizoxin, a macrocyclic lactone antibiotic, as a new antitumor agent against human and murine tumour cells and their vincristine-resistant sublines. Cancer Res. 46, 381–385 (1986)
Jordan, A., Hadfield, J. A., Lawrence, N. J. & McGown, A. T. Tubulin as a target for anticancer drugs: agents which interact with the mitotic spindle. Med. Res. Rev. 18, 259–296 (1998)
Jennessen, J. et al. Secondary metabolite and mycotoxin production by the Rhizopus microsporus group. J. Agric. Food Chem. 53, 1833–1840 (2005)
Kobayashi, H., Iwasaki, S., Yamada, E. & Okuda, S. Biosynthesis of the antimitotic antitumour antibiotic rhizoxin by Rhizopus chinensis; Origins of the carbon atoms. J. Chem. Soc., Chem. Commun. 1702–1703 (1986)
Hopwood, D. A. Genetic contributions to understanding polyketide synthases. Chem. Rev. 97, 2465–2497 (1997)
Nicholson, T. P. et al. Design and utility of oligonucleotide gene probes for fungal polyketide synthases. Chem. Biol. 8, 157–178 (2001)
Piel, J., Hui, D., Fusetani, N. & Matsunaga, S. Targeting modular polyketide synthases with iteratively acting acyltransferases from metagenomes of uncultured bacterial consortia. Environ. Microbiol. 6, 921–927 (2004)
Roberge, M. et al. Cell-based screen for antimitotic agents and identification of analogues of rhizoxin, eleutherobin, and paclitaxel in natural extracts. Cancer Res. 60, 5052–5058 (2000)
Kenny, D. J., Russell, P., Rogers, D., Eley, S. M. & Titball, R. W. In vitro susceptibilities of Burkholderia mallei in comparison to those of other pathogenic Burkholderia spp. Antimicrob. Agents Chemother. 43, 2773–2775 (1999)
Hildebrand, M. et al. Approaches to identify, clone, and express symbiont bioactive metabolite genes. Nat. Prod. Rep. 21, 122–124 (2004)
Piel, J. Metabolites from symbiotic bacteria. Nat. Prod. Rep. 21, 519–538 (2004)
Piel, J. A polyketide synthase-peptide synthetase gene cluster from an uncultured bacterial symbiont of Paederus beetles. Proc. Natl Acad. Sci. USA 99, 14002–14007 (2002)
Piel, J. et al. Antitumor polyketide biosynthesis by an uncultivated bacterial symbiont of the marine sponge Theonella swinhoei. Proc. Natl Acad. Sci. USA 101, 16222–16227 (2004)
Coenye, T. & Vandamme, P. Diversity and significance of Burkholderia species occupying diverse ecological niches. Environ. Microbiol. 5, 719–729 (2003)
Bianciotto, V. et al. An obligately endosymbiontic mycorrhizal fungus itself harbors obligately intracellular bacteria. Appl. Environ. Microbiol. 62, 3005–3010 (1996)
Bonfante, P. Plants, mycorrhizal fungi and endobacteria: a dialog among cells and genomes. Biol. Bull. 204, 215–220 (2003)
Kobayashi, M. et al. Cutaneous zygomycosis: a case report and review of Japanese reports. Mycoses 44, 311–315 (2001)
Ribes, J. A., Vanover-Sams, C. L. & Baker, D. J. Zygomycetes in human disease. Clin. Microbiol. Rev. 13, 236–301 (2000)
He, J. & Hertweck, C. Iteration as programmed event during polyketide formation; molecular analysis of the aureothin biosynthesis gene cluster. Chem. Biol. 10, 1225–1232 (2003)
Thompson, J. D., Gibson, T. J., Plewniak, F., Jeanmougin, F. & Higgins, D. G. The ClustalX windows interface: flexible strategies for multiple alignment aided by quality analysis tools. Nucleic Acids Res. 24, 4876–4882 (1997)
Acknowledgements
We thank A. Perner for MS and HPLC-MS measurements, G.-M. Schwinger for strain cultivation, I. Löschmann for sequencing and A. Hartmann for practical help using the laser microscope. We are grateful to J. Piel for advice and discussions, and H. G. Floss and A. Brakhage for critically reading earlier versions of the manuscript. Financial support by the Leibniz Gemeinschaft is acknowledged.
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Competing interests
The 16S rDNA nucleotide sequences of Rhizopus sp. symbionts have been deposited at the EMBL Nucleotide Sequence Database under the accession numbers AJ938141–AJ938144. Reprints and permissions information is available at npg.nature.com/reprintsandpermissionsu. The authors declare no competing financial interests.
Supplementary information
Supplementary Figure 1
MSn spectrum of rhizoxin (1,) produced by cultivated symbiont. Inset shows diagnostic fork — shape UV spectrum of the triene moiety of 1. (PDF 10489 kb)
Supplementary Figure 2
Generation of symbiont-free Rhizopus strain and reinfection with cultivated symbiont. Agarose (2 %) gel electrophoresis of 16S rDNA PCR products amplified with universal primers. As template served fungal metagenomic DNA of symbiont-free R. microsporus ATCC 62417 (lane 1), and R. microsporus ATCC 62417 after reinfection (lane 2). Lanes 3 and 4 are positive and negative controls, respectively. (PDF 128 kb)
Rights and permissions
About this article
Cite this article
Partida-Martinez, L., Hertweck, C. Pathogenic fungus harbours endosymbiotic bacteria for toxin production. Nature 437, 884–888 (2005). https://doi.org/10.1038/nature03997
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1038/nature03997
This article is cited by
-
Mucormycosis: a rare forgotten but fatal disease—a case report and literature review
Journal of Rare Diseases (2024)
-
Detection and isolation of a new member of Burkholderiaceae-related endofungal bacteria from Saksenaea boninensis sp. nov., a new thermotolerant fungus in Mucorales
IMA Fungus (2023)
-
Klebsiella michiganensis: a nitrogen-fixing endohyphal bacterium from Ustilago maydis
AMB Express (2023)
-
The endohyphal microbiome: current progress and challenges for scaling down integrative multi-omic microbiome research
Microbiome (2023)
-
Nutrient supplementation by genome-eroded Burkholderia symbionts of scale insects
The ISME Journal (2023)
Comments
By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.