Unique infection structures produced by Pseudocercosporella capsellae on oilseed crops Brassica carinata, B. juncea and B. napus in Western Australia

Gunasinghe, N. ORCID: https://orcid.org/0000-0001-8591-0983 and You, M. P. and Clode, P. and Cawthray, G. R. and Barbetti, M. J. (2017) Unique infection structures produced by Pseudocercosporella capsellae on oilseed crops Brassica carinata, B. juncea and B. napus in Western Australia. Plant Pathology, 66 (2). pp. 304-315. ISSN 0032-0862


Abstract

White leaf spot disease (Pseudocercosporella capsellae) is widespread across oilseed, vegetable and forage brassicas. Light (LM) and scanning electron (SEM) microscope studies were undertaken to investigate host–pathogen interactions on cotyledons of resistant and susceptible Brassica carinata, B. juncea and B. napus. Under LM, unique brown structures were present, particularly on susceptible genotypes, in two morphologically distinct forms: first, as thread-like structures within cortical tissue by 24 h post-inoculation (hpi) and secondly, as brown ropy strand structures either within cortical tissues (internal ropy strands), or extruded out through stomatal pores (ropy strand extrusions). Under LM, these brown structures were most prevalent in highly susceptible B. juncea ‘Vardan’ that had both a high incidence within cortical tissue (70%) and of ropy strand extrusions (73%), as did susceptible B. napus ‘Trilogy’ within cortical tissue (60%). Under SEM, both these genotypes showed thread-like structures smaller than hyphae forming highly branched networks and ropy strand-like structures. While there were fewer brown structures in susceptible B. carinata UWA #012 (35%), fine, thread-like structures forming networks were again prominent (SEM). In contrast, for resistant genotypes, brown structures (LM) were of very low frequency or absent; only 5% in resistant B. juncea ‘Dune’ and none in resistant B. napus ‘Hyola 42’ or highly resistant B. carinata ATC94129P. Under SEM, fine, threadlike structures were present in the resistant B. juncea ‘Dune’ and B. napus ‘Hyola 42’. Liquid chromatographic analyses of brown structures revealed that both internal ropy strands within cortical tissues and ropy strand extrusions contained the mycotoxin cercosporin.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Faculty/School / Institute/Centre: No Faculty
Faculty/School / Institute/Centre: No Faculty
Date Deposited: 11 Mar 2021 05:01
Last Modified: 31 Mar 2021 05:59
Uncontrolled Keywords: cercosporin, extrusion structures, infection structures, resistance mechanisms, white leaf spot
Fields of Research (2008): 06 Biological Sciences > 0607 Plant Biology > 060704 Plant Pathology
06 Biological Sciences > 0605 Microbiology > 060505 Mycology
07 Agricultural and Veterinary Sciences > 0703 Crop and Pasture Production > 070308 Crop and Pasture Protection (Pests, Diseases and Weeds)
Fields of Research (2020): 31 BIOLOGICAL SCIENCES > 3107 Microbiology > 310705 Mycology
31 BIOLOGICAL SCIENCES > 3108 Plant biology > 310805 Plant pathology
30 AGRICULTURAL, VETERINARY AND FOOD SCIENCES > 3004 Crop and pasture production > 300409 Crop and pasture protection (incl. pests, diseases and weeds)
Socio-Economic Objectives (2008): 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
B Economic Development > 82 Plant Production and Plant Primary Products > 8205 Winter Grains and Oilseeds > 820502 Canola
B Economic Development > 82 Plant Production and Plant Primary Products > 8202 Horticultural Crops > 820214 Tropical Fruit
Socio-Economic Objectives (2020): 28 EXPANDING KNOWLEDGE > 2801 Expanding knowledge > 280102 Expanding knowledge in the biological sciences
26 PLANT PRODUCTION AND PLANT PRIMARY PRODUCTS > 2603 Grains and seeds > 260302 Canola
26 PLANT PRODUCTION AND PLANT PRIMARY PRODUCTS > 2605 Horticultural crops > 260512 Protected vegetable crops
Identification Number or DOI: https://doi.org/10.1111/ppa.12563
URI: http://eprints.usq.edu.au/id/eprint/41549

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