Genotypic and Phenotypic Characterization of Lettuce Bacterial Pathogen <i>Xanthomonas hortorum</i> pv. <i>vitians</i> Populations Collected in Quebec, Canada
Bacterial leaf spot of lettuce, caused by <i>Xanthomonas hortorum</i> pv. <i>vitians</i>, is an economically important disease worldwide. For instance, it caused around 4 million CAD in losses in only a few months during the winter of 1992 in Florida. Because only one pestici...
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| Format: | Article |
| Language: | English |
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MDPI AG
2021-11-01
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| Series: | Agronomy |
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| Online Access: | https://www.mdpi.com/2073-4395/11/12/2386 |
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| author | Pierre-Olivier Hébert Martin Laforest Dong Xu Marie Ciotola Mélanie Cadieux Carole Beaulieu Vicky Toussaint |
| author_facet | Pierre-Olivier Hébert Martin Laforest Dong Xu Marie Ciotola Mélanie Cadieux Carole Beaulieu Vicky Toussaint |
| author_sort | Pierre-Olivier Hébert |
| collection | DOAJ |
| description | Bacterial leaf spot of lettuce, caused by <i>Xanthomonas hortorum</i> pv. <i>vitians</i>, is an economically important disease worldwide. For instance, it caused around 4 million CAD in losses in only a few months during the winter of 1992 in Florida. Because only one pesticide is registered to control this disease in Canada, the development of lettuce cultivars tolerant to bacterial leaf spot remains the most promising approach to reduce the incidence and severity of the disease in lettuce fields. The lack of information about the genetic diversity of the pathogen, however, impairs breeding programs, especially when disease resistance is tested on newly developed lettuce germplasm lines. To evaluate the diversity of <i>X. hortorum</i> pv. <i>vitians</i>, a multilocus sequence analysis was performed on 694 isolates collected in Eastern Canada through the summers of 2014 to 2017 and two isolates in 1996 and 2007. All isolates tested were clustered into five phylogroups. Six pathotypes were identified following pathogenicity tests conducted in greenhouses, but when phylogroups were compared with pathotypes, no correlation could be drawn. However, in vitro production of xanthan and xanthomonadins was investigated, and isolates with higher production of xanthomonadins were generally causing less severe symptoms on the tolerant cultivar Little Gem. Whole-genome sequencing was undertaken for 95 isolates belonging to the pathotypes identified, and de novo assembly made with reads unmapped to the reference strain’s genome sequence resulted in 694 contigs ranging from 128 to 120,795 bp. Variant calling was performed prior to genome-wide association studies computed with single-nucleotide polymorphisms (SNPs), copy-number variants and gaps. Polymorphisms with significant <i>p</i>-values were only found on the cultivar Little Gem. Our results allowed molecular identification of isolates likely to cause bacterial leaf spot of lettuce, using two SNPs identified through genome-wide association study. |
| first_indexed | 2024-03-10T04:41:46Z |
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| language | English |
| last_indexed | 2024-03-10T04:41:46Z |
| publishDate | 2021-11-01 |
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| series | Agronomy |
| spelling | doaj.art-a26da200276b40bc95b9b070182bbced2023-11-23T03:21:02ZengMDPI AGAgronomy2073-43952021-11-011112238610.3390/agronomy11122386Genotypic and Phenotypic Characterization of Lettuce Bacterial Pathogen <i>Xanthomonas hortorum</i> pv. <i>vitians</i> Populations Collected in Quebec, CanadaPierre-Olivier Hébert0Martin Laforest1Dong Xu2Marie Ciotola3Mélanie Cadieux4Carole Beaulieu5Vicky Toussaint6Saint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Blvd., St-Jean-sur-Richelieu, QC J3B 3E6, CanadaSaint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Blvd., St-Jean-sur-Richelieu, QC J3B 3E6, CanadaSaint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Blvd., St-Jean-sur-Richelieu, QC J3B 3E6, CanadaSaint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Blvd., St-Jean-sur-Richelieu, QC J3B 3E6, CanadaSaint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Blvd., St-Jean-sur-Richelieu, QC J3B 3E6, CanadaDepartment of Biology, Sherbrooke University, 2500 University Blvd., Sherbrooke, QC J1K 2R1, CanadaSaint-Jean-sur-Richelieu Research and Development Centre, Agriculture and Agri-Food Canada, 430 Gouin Blvd., St-Jean-sur-Richelieu, QC J3B 3E6, CanadaBacterial leaf spot of lettuce, caused by <i>Xanthomonas hortorum</i> pv. <i>vitians</i>, is an economically important disease worldwide. For instance, it caused around 4 million CAD in losses in only a few months during the winter of 1992 in Florida. Because only one pesticide is registered to control this disease in Canada, the development of lettuce cultivars tolerant to bacterial leaf spot remains the most promising approach to reduce the incidence and severity of the disease in lettuce fields. The lack of information about the genetic diversity of the pathogen, however, impairs breeding programs, especially when disease resistance is tested on newly developed lettuce germplasm lines. To evaluate the diversity of <i>X. hortorum</i> pv. <i>vitians</i>, a multilocus sequence analysis was performed on 694 isolates collected in Eastern Canada through the summers of 2014 to 2017 and two isolates in 1996 and 2007. All isolates tested were clustered into five phylogroups. Six pathotypes were identified following pathogenicity tests conducted in greenhouses, but when phylogroups were compared with pathotypes, no correlation could be drawn. However, in vitro production of xanthan and xanthomonadins was investigated, and isolates with higher production of xanthomonadins were generally causing less severe symptoms on the tolerant cultivar Little Gem. Whole-genome sequencing was undertaken for 95 isolates belonging to the pathotypes identified, and de novo assembly made with reads unmapped to the reference strain’s genome sequence resulted in 694 contigs ranging from 128 to 120,795 bp. Variant calling was performed prior to genome-wide association studies computed with single-nucleotide polymorphisms (SNPs), copy-number variants and gaps. Polymorphisms with significant <i>p</i>-values were only found on the cultivar Little Gem. Our results allowed molecular identification of isolates likely to cause bacterial leaf spot of lettuce, using two SNPs identified through genome-wide association study.https://www.mdpi.com/2073-4395/11/12/2386bacterial leaf spotpathogenicitygenome-wide association study |
| spellingShingle | Pierre-Olivier Hébert Martin Laforest Dong Xu Marie Ciotola Mélanie Cadieux Carole Beaulieu Vicky Toussaint Genotypic and Phenotypic Characterization of Lettuce Bacterial Pathogen <i>Xanthomonas hortorum</i> pv. <i>vitians</i> Populations Collected in Quebec, Canada Agronomy bacterial leaf spot pathogenicity genome-wide association study |
| title | Genotypic and Phenotypic Characterization of Lettuce Bacterial Pathogen <i>Xanthomonas hortorum</i> pv. <i>vitians</i> Populations Collected in Quebec, Canada |
| title_full | Genotypic and Phenotypic Characterization of Lettuce Bacterial Pathogen <i>Xanthomonas hortorum</i> pv. <i>vitians</i> Populations Collected in Quebec, Canada |
| title_fullStr | Genotypic and Phenotypic Characterization of Lettuce Bacterial Pathogen <i>Xanthomonas hortorum</i> pv. <i>vitians</i> Populations Collected in Quebec, Canada |
| title_full_unstemmed | Genotypic and Phenotypic Characterization of Lettuce Bacterial Pathogen <i>Xanthomonas hortorum</i> pv. <i>vitians</i> Populations Collected in Quebec, Canada |
| title_short | Genotypic and Phenotypic Characterization of Lettuce Bacterial Pathogen <i>Xanthomonas hortorum</i> pv. <i>vitians</i> Populations Collected in Quebec, Canada |
| title_sort | genotypic and phenotypic characterization of lettuce bacterial pathogen i xanthomonas hortorum i pv i vitians i populations collected in quebec canada |
| topic | bacterial leaf spot pathogenicity genome-wide association study |
| url | https://www.mdpi.com/2073-4395/11/12/2386 |
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