scholarly journals Calcineurin Is Required for Sclerotial Development and Pathogenicity of Sclerotinia sclerotiorum in an Oxalic Acid-Independent Manner

2006 ◽  
Vol 19 (6) ◽  
pp. 682-693 ◽  
Author(s):  
A. Harel ◽  
S. Bercovich ◽  
O. Yarden
Keyword(s):  
Cell Wall ◽  
Oxalic Acid ◽  
Sclerotinia Sclerotiorum ◽  
Cell Wall Degrading Enzymes ◽  
Independent Manner ◽  
Worldwide Distribution ◽  
Cation Homeostasis ◽  
Increased Sensitivity ◽  
Synthase Inhibitor ◽  
Sclerotial Development

Sclerotinia sclerotiorum is a necrotrophic, omnivorous plant pathogen with worldwide distribution. Sclerotia of S. sclerotiorum are pigmented, multihyphal structures that play a central role in the life and infection cycles of this pathogen. Calcineurin, a Ser/Thr phosphatase linked to several signal-transduction pathways, plays a key role in the regulation of cation homeostasis, morphogenesis, cell-wall integrity, and pathogenesis in fungi. We demonstrate that calcineurin expression in S. sclerotiorum is altered in a phase-specific manner during sclerotial development. Inhibition of calcineurin by FK506, cysclosporin A, or inducible antisense calcineurin expression impaired sclerotial development at the prematuration phase and increased germination of preformed sclerotia. Induction of antisense calcineurin expression in S. sclerotiorum resulted in reduced pathogenesis on tomato and Arabidopsis. However, secretion of oxalic acid, a key virulence factor of S. scle-rotiorum, was not altered. Inhibition of calcineurin conferred a reduction in cell wall β-1,3-glucan content and increased sensitivity to cell-wall-degrading enzymes and to the glucan synthase inhibitor caspofungin. Thus, calcineurin plays a major role in both sclerotial development and pathogenesis of S. sclerotiorum and, most likely, other phyto-pathogens.

Mycoparasitism studies of Trichoderma harzianum against Sclerotinia sclerotiorum: evaluation of antagonism and expression of cell wall-degrading enzymes genes

2014 ◽  
Vol 36 (10) ◽  
pp. 2095-2101 ◽  
Author(s):  
Rogério Fraga Troian ◽  
Andrei Stecca Steindorff ◽  
Marcelo Henrique Soller Ramada ◽  
Walquiria Arruda ◽  
Cirano José Ulhoa
Keyword(s):  
Cell Wall ◽  
Sclerotinia Sclerotiorum ◽  
Trichoderma Harzianum ◽  
Cell Wall Degrading Enzymes ◽  
Degrading Enzymes

scholarly journals Expression of the Histidine Kinase Gene Sshk Correlates with Dimethachlone Resistance in Sclerotinia sclerotiorum

2019 ◽  
Vol 109 (3) ◽  
pp. 395-401 ◽  
Author(s):  
Jinli Li ◽  
Fuxing Zhu ◽  
Jianhong Li
Keyword(s):  
Cell Wall ◽  
Sclerotinia Sclerotiorum ◽  
Mycelial Growth ◽  
Sodium Dodecyl ◽  
Pathogenic Fungi ◽  
Kinase Gene ◽  
Group Iii ◽  
Major Mechanism ◽  
Increased Sensitivity ◽  
Sclerotium Production

Histidine kinases (HK) are implicated in virulence, vegetative mycelial growth, and osmotic and oxidative responses in pathogenic fungi. Our previous work showed that transcriptional levels of the group III HK gene Sshk are higher in field dimethachlone-resistant isolates of Sclerotinia sclerotiorum compared with sensitive isolates. However, it is not clear whether the overexpression of Sshk is the major mechanism for resistance to dimethachlone. In this study, we constructed Sshk silencing and overexpression vectors and assessed dimethachlone resistance levels, virulence, mycelial growth, and sensitivity to osmotic stress for the Sshk-silenced and -overexpression transformants. Overexpression of Sshk resulted in resistance to dimethachlone and increased sensitivity to various stresses and to the cell-wall-perturbing agents sodium dodecyl sulfate (SDS) and Congo red (CR). Compared with the parent isolate, Sshk-silenced transformants had reduced resistance to dimethachlone, significantly higher (P < 0.05) mycelial growth and virulence, and lower sclerotium production, and were less sensitive to various exogenous stresses such as sodium chloride. Compared with the parent sensitive isolate HLJMG1, dimethachlone resistance ratios of the three overexpression transformants ∆C101, ∆C21, and ∆C10 increased 168.1-, 189.5-, and 221.2-fold, respectively. The three overexpression transformants were more sensitive to CR and SDS than their parent isolate. These findings suggest that overexpression of Sshk is a major mechanism for dimethachlone resistance in some isolates of S. sclerotiorum, and that Sshk plays an important role in maintaining the integrity of the cell wall. Our findings reveal a novel molecular mechanism for dimethachlone resistance in plant-pathogenic fungi.

scholarly journals The Sclerotinia sclerotiorum pac1 Gene Is Required for Sclerotial Development and Virulence

2003 ◽  
Vol 16 (9) ◽  
pp. 785-795 ◽  
Author(s):  
Jeffrey A. Rollins
Keyword(s):  
Oxalic Acid ◽  
Sclerotinia Sclerotiorum ◽  
Acid Production ◽  
Plant Pathogens ◽  
Gene Replacement ◽  
Loss Of Function ◽  
Physiological Processes ◽  
Gene Transcripts ◽  
Sclerotial Development

The synergistic activities of oxalic acid and endopolygalacturonases are thought to be essential for full virulence of Sclerotinia sclerotiorum and other oxalate-producing plant pathogens. Both oxalic acid production and endopolygalacturonase activity are regulated by ambient pH. Since many gene products with pH-sensitive activities are regulated by the PacC transcription factor in Aspergillus nidulans, we functionally characterized a pacC gene homolog, pac1, from S. sclerotiorum. Mutants with loss-of-function alleles of the pac1 locus were created by targeted gene replacement. In vitro mycelial growth of these pac1 mutants was normal at acidic pH, but growth was inhibited as culture medium pH was increased. Development and maturation of sclerotia in culture was also aberrant in these pac1 replacement mutants. Although oxalic acid production remained alkaline pH-responsive, the kinetics and magnitude of oxalate accumulation were dramatically altered. Additionally, maximal accumulation of endopolygalacturonase gene transcripts (pg1) was shifted to higher ambient pH. Virulence in loss-of-function pac1 mutants was dramatically reduced in infection assays with tomato and Arabidopsis. Based on these results, pac1 appears to be necessary for the appropriate regulation of physiological processes important for pathogenesis and development of S. sclerotiorum.

scholarly journals Mycoparasitism illuminated by genome sequencing and digital gene expression profiling of Coniothyrium minitans, an important biocontrol fungus of the plant pathogen Sclerotinia sclerotiorum

2019 ◽  
Author(s):  
Huizhang Zhao ◽  
Ting Zhou ◽  
Jiatao Xie ◽  
Jiasen Cheng ◽  
Tao Chen ◽  
...  
Keyword(s):  
Cell Wall ◽  
Secondary Metabolites ◽  
Sclerotinia Sclerotiorum ◽  
Plant Pathogen ◽  
Hydrolase Activity ◽  
Secretory Proteins ◽  
Peptidase Activity ◽  
Serine Hydrolase ◽  
Cell Wall Degrading Enzymes ◽  
Degrading Enzymes

Abstract BackgroundConiothyrium minitans is a mycoparasite of the notorious plant pathogen Sclerotinia sclerotiorum. To further understand the parasitism of C. minitans, here, we assembled and analyzed its genome by combining transcriptome data.ResultsThe genome of C. minitans strain ZS-1 was 39.77 Mb in 350 scaffolds. A total of 11437 predicted genes and proteins were annotated, and 30.8% of blast hits matched proteins encoded by Paraphaeosphaeria sporulosa, a worldwide soil fungus. The transcriptome of strain ZS-1 during the early interaction at 0 h, 4 h and 12 h with its host was analyzed. The detected expressed genes were involved in response to host defenses, including cell wall-degrading enzymes, transporters, secretory proteins and secondary metabolites. The fungal cell wall-degrading enzymes belonged to the GH16, GH18, and GH72 classes in CAZymes, and some were significantly up-regulated during mycoparasitism. Most of the monocarboxylate transporter genes of the major facilitator superfamily and all the detected ABC transporters, especially the heavy metal transporters, were significantly up-regulated. Approximately 8% of the 11437 proteins in C. minitans were predicted to be secretory proteins, with catalytic activity, hydrolase activity, peptidase activity and serine hydrolase activity enriched in molecular function. Most genes involved in serine hydrolase activity were significantly up-regulated during mycoparasitism.ConclusionThis assemble genome and genome-wide expression study demonstrate that the mycoparasitism process of C. minitans is complex and a series of genes or proteins would be deployed by C. minitans to invade successfully the host. Our study provides insights into the mechanisms of the mycoparasitism between C. minitans and S. sclerotiorum and clues to excavate active secondary metabolites from C. minitans.

scholarly journals Pathogenicity and Sclerotial Development of Sclerotinia sclerotiorum: Involvement of Oxalic Acid and Chitin Synthesis

1995 ◽  
Author(s):  
Martin B. Dickman ◽  
Oded Yarden
Keyword(s):  
Oxalic Acid ◽  
Sclerotinia Sclerotiorum ◽  
Plant Pathogens ◽  
Detailed Examination ◽  
Genetically Engineered ◽  
Molecular Techniques ◽  
Chitin Synthesis ◽  
Dry Bean ◽  
Fungal Plant Pathogens ◽  
Sclerotial Development

Sclerotinia sclerotiorum (Lib.) de Bary is among the world's most successful and omnivorous fungal plant pathogens. Included in the nearly 400 species of plants reported as hosts to this fungus are canola, alfalfa, soybean, sunflower, dry bean and potato. The general inability to develop resistant germplasm with these economically important crops to this pathogen has focused attention on the need for a more detailed examination of the pathogenic determinants involved in disease development. A mechanistic understanding of the successful strategy(ies) used by S. sclerotiorum in colonizing host plants and their linkage to fungal development may provide targets and/or novel approaches with which to design resistant crop plants. This proposal involved experiments which were successful in generating genetically-engineered plants harboring resistance to S. sclerotiorum, the establishment and improvement of molecular tools for the study of this pathogen and the analysis of the linkage between pathogenicity, sclerotial morphogenesis and two biosynthetic pathways: oxalic acid production and chitin synthesis. The highly collaborative project has improved our understanding of S. sclerotiorum pathogenicity, established reliable molecular techniques to facilitate experimental manipilation and generated transgenic plants which are resistant to this econimically important fungus.

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