Oxaloacetate acetylhydrolase gene mutants of <i><scp>S</scp>clerotinia sclerotiorum</i> do not accumulate oxalic acid, but do produce limited lesions on host plants

Liang, Xiaofei; Liberti, D.; Li, Moyi; Kim, Youngtae; Hutchens, Andrew; Wilson, R. Bryce; Rollins, Jeffrey A.

doi:10.1111/mpp.12211

Cited by 116 publications

(158 citation statements)

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“…OA can be synthesized from a variety of precursors, but in fungi the most common mechanism is through the hydrolysis of oxaloacetate to form OA and carbon dioxide. An oxaloacetate acetyl hydrolase (OAH) has been characterized in S. sclerotiorum [114] and disruption of the OAH gene in Aspergillus niger , B. cinerea [115] and S. sclerotiorum leads to loss of oxalic acid production and reduced virulence [116]. In the current study, the S. sclerotiorum OAH gene (SS1G_08218) was expressed from 1 hpi, but only up-regulated at 48 hpi with 5- fold greater levels than the inoculum.…”

Section: Resultsmentioning

confidence: 71%

“…Release of OA causes a reduction in ambient pH, which stimulates hydrolytic enzyme production throughout the course of the infection [112, 118], as well as sclerotogenesis during its final stages [7, 119], though OA may not be the sole determinant affecting tissue acidification [120]. Interestingly, fine-tuning of OA levels through the activity of OA biogenic [121] and degradative [116] enzymes appears to be critical for early host-pathogen interactions as well, including compound appressorium formation and lesion expansion.…”

Section: Resultsmentioning

confidence: 99%

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Changes in the Sclerotinia sclerotiorum transcriptome during infection of Brassica napus

et al. 2017

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Background Sclerotinia sclerotiorum causes stem rot in Brassica napus, which leads to lodging and severe yield losses. Although recent studies have explored significant progress in the characterization of individual S. sclerotiorum pathogenicity factors, a gap exists in profiling gene expression throughout the course of S. sclerotiorum infection on a host plant. In this study, RNA-Seq analysis was performed with focus on the events occurring through the early (1 h) to the middle (48 h) stages of infection.ResultsTranscript analysis revealed the temporal pattern and amplitude of the deployment of genes associated with aspects of pathogenicity or virulence during the course of S. sclerotiorum infection on Brassica napus. These genes were categorized into eight functional groups: hydrolytic enzymes, secondary metabolites, detoxification, signaling, development, secreted effectors, oxalic acid and reactive oxygen species production. The induction patterns of nearly all of these genes agreed with their predicted functions. Principal component analysis delineated gene expression patterns that signified transitions between pathogenic phases, namely host penetration, ramification and necrotic stages, and provided evidence for the occurrence of a brief biotrophic phase soon after host penetration.ConclusionsThe current observations support the notion that S. sclerotiorum deploys an array of factors and complex strategies to facilitate host colonization and mitigate host defenses. This investigation provides a broad overview of the sequential expression of virulence/pathogenicity-associated genes during infection of B. napus by S. sclerotiorum and provides information for further characterization of genes involved in the S. sclerotiorum-host plant interactions.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-017-3642-5) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 71%

Section: Resultsmentioning

confidence: 99%

Changes in the Sclerotinia sclerotiorum transcriptome during infection of Brassica napus

et al. 2017

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“…In conclusion, this study has shown that S. sclerotiorum infects its host in two phases: phase I – primary lesion formation where OA accumulation is low and may not be significant, and phase II – colonization where OA is required. The low OA levels observed during primary lesion formation in OxO‐OE has also been noted by Heller & Witt‐Geiges () and is in agreement with the observation that primary lesions can form in the presence of OA‐reduced mutants (Cessna et al ., ; Kim et al ., ; Williams et al ., ) and OA‐minus mutants that produce no OA (Liang et al ., ; Xu et al ., ). It is becoming apparent to the authors, and others, (Kabbage et al ., ; Liang et al ., ; Xu et al ., ), that factors other than OA have major roles during primary lesion formation.…”

Section: Discussionmentioning

confidence: 99%

“…Furthermore, Liang et al . () and Xu et al . () have shown, independently, that S. sclerotiorum knockout mutants that generate no OA can establish primary lesions but have limited ability to colonize the host.…”

Section: Introductionmentioning

confidence: 90%

Histopathology of Sclerotinia sclerotiorum infection and oxalic acid function in susceptible and resistant soybean

et al. 2016

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The success of the necrotrophic fungus Sclerotinia sclerotiorum is largely dependent on its major virulence factor, oxalic acid (OA). Virulence is lost in transgenic plants that express OA degrading enzymes, e.g. oxalate oxidase (OxO). The histopathology of S. sclerotiorum infection and OA accumulation was examined in a transgenic soybean line over-expressing OxO (OxO-OE) and its isogenic parent (WT). In situ flower inoculation showed that the OxO-OE plants were highly resistant to the pathogen while the WT parents were susceptible. This difference in resistance was not apparent in the floral tissues, as aggressive hyphal activity was similar on both hosts, showing that high OxO activity and low OA accumulation in OxO-OE was not a deterrent. However, the process of fungal infection on excised leaf tissue differed on the two hosts. Primary lesions developed and showed similar severe ultrastructural damage on both hosts but rapid lesion expansion (colonization) proceeded only on the WT, concomitant with OA accumulation. Oxalic acid rose in OxO-OE 1 day post-inoculation and did not change over the following 3 days, showing that colonization can be blocked by maintaining low levels of OA. However, OxO degradation of OA did not deter initial host penetration and primary lesion formation. This shows that OA, the major virulence factor of S. sclerotiorum, is critical for host colonization but may not be required during primary lesion formation, suggesting that other factors are contributing to the establishment of the primary lesion.

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“…S. sclerotiorum colonization is associated with many enzymes that are capable of digesting and degrading the cell wall of the host. In addition, several authors have associated the production of oxalic acid (OA) with virulence (HAREL et al, 2006;KIM et al, 2008;WALZ et al, 2008;LIANG et al, 2015). Therefore, some susceptibility screening assays are based on the responses of different genotypes to oxalic acid (GONÇALVES;SANTOS, 2010), however, the authors are not aware of any publications assessing the levels of resistance of soybean to S. sclerotiorum based on the wilting responses of OA, as has been efficiently used for common bean (KOLKMAN; KELLLY, 2000;ANTONIO et al, 2008).…”

Section: Introductionmentioning

confidence: 99%

Different methods of assessing susceptibility of soybean genotypes to white mold

Hüller¹,

Filho²,

Pierre³

et al. 2016

Biosci. J.

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ABSTRACT:White mold caused by the fungus Sclerotinia sclerotiorum is an important disease in relation to soybean. The use of less susceptible genotypes can be a productive strategy in the management of this disease, and the development of an appropriate methodology for soybean inoculation is useful for the differentiation of disease-resistant genotypes. The present study aimed to assess the susceptibility of 77 soybean genotypes based on their reaction to oxalic acid, as well as to determine correlations between three traditional disease assay methods (detached leaf, non-wounded stem and straw tests) and the results of the oxalic acid assay. Oxalic acid susceptibility was assessed by using a wilting score scale. For the other methods, the severity of disease symptoms was assessed. To compare methodologies, the values obtained for the genotypes using each method were categorized into classes, and a severity index was used to represent individuals within each class. All the methods used were efficient for the differentiation of soybean genotypes in terms of susceptibility to S. sclerotiorum; however, the behavior of the genotypes depended on the inoculation method adopted. Even though no significant relationship was identified between the severities of the damage resulting from the methodologies, the rankings acquired from the methods strongly agreed. The oxalic acid method was the most rapid, the least laborious, and was the cheapest compared with the other methods that were used.

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Oxaloacetate acetylhydrolase gene mutants of Sclerotinia sclerotiorum do not accumulate oxalic acid, but do produce limited lesions on host plants

Cited by 116 publications

References 53 publications

Changes in the Sclerotinia sclerotiorum transcriptome during infection of Brassica napus

Changes in the Sclerotinia sclerotiorum transcriptome during infection of Brassica napus

Histopathology of Sclerotinia sclerotiorum infection and oxalic acid function in susceptible and resistant soybean

Different methods of assessing susceptibility of soybean genotypes to white mold

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