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Tobias PA, Schwessinger B, Deng CH, Wu C, Dong C, Sperschneider J, Jones A, Lou Z, Zhang P, Sandhu K, Smith GR, Tibbits J, Chagné D, Park RF. Austropuccinia psidii, causing myrtle rust, has a gigabase-sized genome shaped by transposable elements. G3 (Bethesda) 2021; 11:jkaa015. [PMID: 33793741 PMCID: PMC8063080 DOI: 10.1093/g3journal/jkaa015] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 10/26/2020] [Indexed: 02/06/2023]
Abstract
Austropuccinia psidii, originating in South America, is a globally invasive fungal plant pathogen that causes rust disease on Myrtaceae. Several biotypes are recognized, with the most widely distributed pandemic biotype spreading throughout the Asia-Pacific and Oceania regions over the last decade. Austropuccinia psidii has a broad host range with more than 480 myrtaceous species. Since first detected in Australia in 2010, the pathogen has caused the near extinction of at least three species and negatively affected commercial production of several Myrtaceae. To enable molecular and evolutionary studies into A. psidii pathogenicity, we assembled a highly contiguous genome for the pandemic biotype. With an estimated haploid genome size of just over 1 Gb (gigabases), it is the largest assembled fungal genome to date. The genome has undergone massive expansion via distinct transposable element (TE) bursts. Over 90% of the genome is covered by TEs predominantly belonging to the Gypsy superfamily. These TE bursts have likely been followed by deamination events of methylated cytosines to silence the repetitive elements. This in turn led to the depletion of CpG sites in TEs and a very low overall GC content of 33.8%. Compared to other Pucciniales, the intergenic distances are increased by an order of magnitude indicating a general insertion of TEs between genes. Overall, we show how TEs shaped the genome evolution of A. psidii and provide a greatly needed resource for strategic approaches to combat disease spread.
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Affiliation(s)
- Peri A Tobias
- School of Life and Environmental Sciences, University of Sydney, Camperdown, NSW 2006, Australia
- Plant & Food Research Australia, SA 5064, Australia
| | - Benjamin Schwessinger
- Australia Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Cecilia H Deng
- The New Zealand Institute for Plant and Food Research Limited, Auckland 1142, New Zealand
| | - Chen Wu
- The New Zealand Institute for Plant and Food Research Limited, Auckland 1142, New Zealand
| | - Chongmei Dong
- Plant Breeding Institute, University of Sydney, Narellan, NSW 2567, Australia
| | - Jana Sperschneider
- Biological Data Science Institute, The Australian National University, Canberra, ACT, 2600, Australia
| | - Ashley Jones
- Australia Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Zhenyan Lou
- Australia Research School of Biology, The Australian National University, Acton, ACT 2601, Australia
| | - Peng Zhang
- Plant Breeding Institute, University of Sydney, Narellan, NSW 2567, Australia
| | - Karanjeet Sandhu
- Plant Breeding Institute, University of Sydney, Narellan, NSW 2567, Australia
| | - Grant R Smith
- The New Zealand Institute for Plant and Food Research Limited, Christchurch 8140, New Zealand
| | - Josquin Tibbits
- Agriculture Victoria Department of Jobs, Precincts and Regions, Bundoora, VIC 3083, Australia
| | - David Chagné
- The New Zealand Institute for Plant & Food Research, Palmerston North 4442, New Zealand
| | - Robert F Park
- Plant Breeding Institute, University of Sydney, Narellan, NSW 2567, Australia
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