Phenotypic and phylogenetic studies associated with the crucifer white leaf spot pathogen, Pseudocercosporella capsellae, in Western Australia

Gunasinghe, N. and You, M. P. and Barbetti, M. J. (2016) Phenotypic and phylogenetic studies associated with the crucifer white leaf spot pathogen, Pseudocercosporella capsellae, in Western Australia. Plant Pathology, 65 (2). pp. 205-217. ISSN 0032-0862

Abstract

Pseudocercosporella capsellae (white leaf spot disease) is an important disease on crucifers. Fifty four single-conidial isolates collected from Brassica juncea (Indian mustard), B. napus (oilseed rape), B. rapa (turnip), and Raphanus raphanistrum (wild radish) across Western Australia were investigated for differences in pathogenicity and virulence using cotyledon screening tests, genetic differences using Internal Transcribed Spacer (ITS) sequencing and phylogenetic analysis, and growth rates on potato dextrose, V8 juice and malt extract agars. All isolates from the four crucifer hosts were pathogenic on the three test species: B. juncea, B. napus and R. raphanistrum, but showed differences in levels of virulence. Overall, isolates from B. juncea, B. napus and B. rapa showed greatest virulence on B. juncea, least on R. raphanistrum and intermediate virulence on B. napus. Isolates from R. raphanistrum showed greatest virulence on B. juncea, least on B. napus and intermediate virulence on R. raphanistrum. Growth and production of a purple-pink pigment indicative of cercosporin was greatest on malt extract agar and cercosporin production on V8 juice agar was positively correlated with virulence of isolates on B. juncea and B. napus. ITS sequencing and phylogenetic analysis showed that isolates collected from B. napus, B. juncea and B. rapa, in general and with few exceptions, had a high degree of genetic similarity. In contrast, isolates from R. raphanistrum were clearly differentiated from isolate groups collected from Brassica hosts. P. capsellae reference isolates from other countries generally grouped into a single separate cluster, highlighting the genetic distinctiveness of Western Australian isolates.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version cannot be displayed due to copyright restrictions.
Faculty / Department / School: No Faculty
Date Deposited: 01 Mar 2017 04:38
Last Modified: 02 Mar 2018 03:41
Uncontrolled Keywords: Pseudocercosporella capsellae, white leaf spot, genetic variation, phenotypic variation
Fields of Research : 07 Agricultural and Veterinary Sciences > 0703 Crop and Pasture Production > 070308 Crop and Pasture Protection (Pests, Diseases and Weeds)
Socio-Economic Objective: D Environment > 96 Environment > 9604 Control of Pests, Diseases and Exotic Species > 960413 Control of Plant Pests, Diseases and Exotic Species in Farmland, Arable Cropland and Permanent Cropland Environments
Identification Number or DOI: 10.1111/ppa.12402
URI: http://eprints.usq.edu.au/id/eprint/30737

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