A phylogenetically distinct lineage of Pyrenopeziza brassicae associated with chlorotic leaf spot of Brassicaceae in North America

A - Papers appearing in refereed journals

Carmody, S., King, K. M., Ocamb, C., Fraaije, B. A., West, J. S. and Du Toit, L. 2019. A phylogenetically distinct lineage of Pyrenopeziza brassicae associated with chlorotic leaf spot of Brassicaceae in North America . Plant Pathology. 69 (3), pp. 518-537. https://doi.org/10.1111/ppa.13137

AuthorsCarmody, S., King, K. M., Ocamb, C., Fraaije, B. A., West, J. S. and Du Toit, L.
Abstract

Light leaf spot, caused by the ascomycete Pyrenopeziza brassicae Sutton & Rawlinson, is an established disease of Brassicaceae in the United Kingdom (UK), continental Europe, and Oceania (OC, including New Zealand and Australia). The disease was reported in North America (NA) for the first time in 2014 on Brassica spp. in the Willamette Valley of western Oregon, followed by detection in Brassica juncea cover crops and on B. rapa weeds in northwestern Washington in 2016. Preliminary DNA sequence data and field observations suggest that isolates of the pathogen present in NA might be distinct from those in the UK, continental Europe, and OC. Comparisons of isolates from these regions genetically (multilocus sequence analysis, MAT gene sequences, and rep-PCR DNA fingerprinting), pathogenically (B. rapa inoculation studies), biologically (sexual compatibility), and morphologically (colony and conidial morphology) demonstrated two genetically distinct evolutionary lineages. Lineage 1 comprised isolates from the UK, continental Europe, and OC, and included the P. brassicae type specimen. Lineage 2 contained the NA isolates associated with recent disease outbreaks in the Pacific Northwest region of the USA. Symptoms caused by isolates of the two lineages on B. rapa and B. juncea differed, so ‘chlorotic leaf spot’ is proposed for the disease caused by lineage 2 isolates of P. brassicae. Isolates of the two lineages differed in genetic diversity as well as sensitivity to the fungicides carbendazim and prothioconazole.

KeywordsBrassicaceae; Chlorotic leaf spot; Light leaf spot; Pacific Northwest USA; Phylogenetic lineage; Pyrenopeziza brassicae
Year of Publication2019
JournalPlant Pathology
Journal citation69 (3), pp. 518-537
Digital Object Identifier (DOI)https://doi.org/10.1111/ppa.13137
Open accessPublished as ‘gold’ (paid) open access
FunderBBSRC Industrial Strategy Challenge
Funder project or codePathogen surveillance and monitoring
Publisher's version
Accepted author manuscript
Output statusPublished
Publication dates
OnlineDec 2019
Publication process dates
Accepted09 Dec 2019
PublisherWiley
ISSN0032-0862

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