Bacterial and fungal endophyte communities in healthy and diseased oilseed rape and their potential for biocontrol of Sclerotinia and Phoma disease

AbstractPhoma stem canker (caused by the ascomycetes Leptosphaeria maculans and Leptosphaeria biglobosa) is an important disease of oilseed rape. Its effect on endophyte communities in roots and shoots and the potential of endophytes to promote growth and control diseases of oilseed rape (OSR) was investigated. Phoma stem canker had a large effect especially on fungal but also on bacterial endophyte communities. Dominant bacterial genera were Pseudomonas, followed by Enterobacter, Serratia, Stenotrophomonas, Bacillus and Staphylococcus. Achromobacter, Pectobacter and Sphingobacterium were isolated only from diseased plants, though in very small numbers. The fungal genera Cladosporium, Botrytis and Torula were dominant in healthy plants whereas Alternaria, Fusarium and Basidiomycetes (Vishniacozyma, Holtermaniella, Bjerkandera/Thanatephorus) occurred exclusively in diseased plants. Remarkably, Leptosphaeria biglobosa could be isolated in large numbers from shoots of both healthy and diseased plants. Plant growth promoting properties (antioxidative activity, P-solubilisation, production of phytohormones and siderophores) were widespread in OSR endophytes. Although none of the tested bacterial endophytes (Achromobacter, Enterobacter, Pseudomonas, Serratia and Stenotrophomonas) promoted growth of oilseed rape under P-limiting conditions or controlled Phoma disease on oilseed rape cotyledons, they significantly reduced incidence of Sclerotinia disease. In the field, a combined inoculum consisting of Achromobacter piechaudii, two pseudomonads and Stenotrophomonas rhizophila tendencially increased OSR yield and reduced Phoma stem canker.

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Occurrence of a New Subclade of Leptosphaeria biglobosa in Western Australia

Phytopathology ◽

10.1094/phyto-98-3-0321 ◽

2008 ◽

Vol 98 (3) ◽

pp. 321-329 ◽

Cited By ~ 30

Author(s):

L. Vincenot ◽

M. H. Balesdent ◽

H. Li ◽

M. J. Barbetti ◽

K. Sivasithamparam ◽

...

Keyword(s):

Oilseed Rape ◽

Mating Type ◽

Western Australia ◽

Leptosphaeria Maculans ◽

Stem Canker ◽

Tubulin Genes ◽

Wide Scale ◽

Scale Characterization ◽

Leptosphaeria Biglobosa ◽

Β Tubulin

Stem canker of crucifers is caused by an ascomycete species complex comprising of two main species, Leptosphaeria maculans and L. biglobosa. These are composed of at least seven distinct subclades based on biochemical data or on sequences of internal transcribed spacer (ITS), the mating type MAT1-2 or fragments of actin or β-tubulin genes. In the course of a wide-scale characterization of the race structure of L. maculans from Western Australia, a few isolates from two locations failed to amplify specific sequences of L. maculans, i.e., the mating-type or minisatellite alleles. Based on both pathogenicity tests and ITS size, these isolates were classified as belonging to the L. biglobosa species. Parsimony and distance analyses performed on ITS, actin and β-tubulin sequences revealed that these isolates formed a new L. biglobosa subclade, more related to the Canadian L. biglobosa ‘canadensis’ subclade than to the L. biglobosa ‘australensis’ isolates previously described in Australia (Victoria). They are termed here as L. biglobosa ‘occiaustralensis’. These isolates were mainly recovered from resistant oilseed rape cultivars that included the Brassica rapa sp. sylvestris-derived resistance source, but not from the susceptible cv. Westar. The pathogenicity of L. biglobosa ‘occiaustralensis’ to cotyledons of most oilseed rape genotypes was higher than that of L. biglobosa ‘canadensis’ or L. biglobosa ‘australensis’ isolates.

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Assessing Quantitative Resistance against Leptosphaeria maculans (Phoma Stem Canker) in Brassica napus (Oilseed Rape) in Young Plants

PLoS ONE ◽

10.1371/journal.pone.0084924 ◽

2014 ◽

Vol 9 (1) ◽

pp. e84924 ◽

Cited By ~ 23

Author(s):

Yong-Ju Huang ◽

Aiming Qi ◽

Graham J. King ◽

Bruce D. L. Fitt

Keyword(s):

Brassica Napus ◽

Oilseed Rape ◽

Quantitative Resistance ◽

Leptosphaeria Maculans ◽

Stem Canker ◽

Phoma Stem Canker

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Dissemination of Information About Management Strategies and Changes in Farming Practices for the Exploitation of Resistance to Leptosphaeria maculans (Phoma Stem Canker) in Oilseed Rape Cultivars

European Journal of Plant Pathology ◽

10.1007/s10658-005-2501-4 ◽

2006 ◽

Vol 114 (1) ◽

pp. 117-126 ◽

Cited By ~ 21

Author(s):

P. Gladders ◽

N. Evans ◽

S. Marcroft ◽

X. Pinochet

Keyword(s):

Oilseed Rape ◽

Management Strategies ◽

Leptosphaeria Maculans ◽

Stem Canker ◽

Farming Practices ◽

Phoma Stem Canker

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A New Subclade of Leptosphaeria biglobosa Identified from Brassica rapa

International Journal of Molecular Sciences ◽

10.3390/ijms20071668 ◽

2019 ◽

Vol 20 (7) ◽

pp. 1668 ◽

Cited By ~ 1

Author(s):

Zhongwei Zou ◽

Xuehua Zhang ◽

Paula Parks ◽

Lindsey du Toit ◽

Angela Van de Wouw ◽

...

Keyword(s):

Brassica Rapa ◽

Phylogenetic Trees ◽

Single Gene ◽

Leptosphaeria Maculans ◽

Stem Canker ◽

Willamette Valley ◽

Gene Sequences ◽

Distance Analysis ◽

Pathogenicity Tests ◽

Leptosphaeria Biglobosa

Blackleg (Phoma stem canker) of crucifers is a globally important disease caused by the ascomycete species complex comprising of Leptosphaeria maculans and Leptosphaeria biglobosa. Six blackleg isolates recovered from Brassica rapa cv. Mizspoona in the Willamette Valley of Oregon were characterized as L. biglobosa based on standard pathogenicity tests and molecular phylogenetic analysis. These isolates were compared to 88 characterized L. biglobosa isolates from western Canada, 22 isolates from Australia, and 6 L. maculans isolates from Idaho, USA using maximum parsimony and distance analysis of phylogenetic trees generated from the ITS rDNA (internal transcribed spacer rDNA) sequence, and the actin and β-tubulin gene sequences. The L. biglobosa isolates derived from B. rapa collected in Oregon formed a separate subclade based on concatenated gene sequences or a single gene sequence, regardless of the analyses. Pathogenicity tests showed that these isolates failed to infect either resistant or susceptible B. napus cultivars, but caused severe symptoms on three B. rapa cultivars (Accession number: UM1113, UM1112, and UM1161), a B. oleracea var. capitata (cabbage) cultivar (Copenhagen Market), and two B. juncea cultivars (CBM, a common brown Mustard, and Forge). These findings demonstrated that the L. biglobosa isolates derived from a B. rapa crop in Oregon were genetically distinct from existing species of L. biglobosa, and constitute a new subclade, herein proposed as L. biglobosa ‘americensis’.

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