Involvement and contribution to virulence of Endo-Beta-1,4-Xilanases of Fusarium Graminearum during host infection
Bibliographic record
Abstract
Fusarium graminearum is the fungal pathogen mainly responsible for Fusarium head blight (FHB) of cereal crops, which attacks wheat spikes, reducing crop production and quality of grain by producing trichothecene mycotoxins. Several cytohistological studies showed that spike infection is associated with the production of cell wall degrading enzymes. Wheat tissue, as in other commelinoid monocot plants, is particularly rich in xylan which can be hydrolyzed by fungal endo-β-1,4-xylanase. The FGSG_03624 is one of the most expressed xylanase genes in wheat spikes 3 days after inoculation and was heterologously expressed in the yeast Pichia pastoris. The recombinant protein (22.7 kDa) possessed xylanase activity and induced cell death and hydrogen peroxide accumulation in wheat leaves infiltrated with 10 ng/μl or in wheat glume surface treated with 20 ng/μl. This effect reflects that observed with other described fungal xylanases (from Trichoderma reesei, T. viride and Botrytis cinerea) with which the FGSG_03624 protein shares a stretch of amino acids reported as essential for elicitation of necrotic responses. Several F. graminearum mutants with the FGSG_03624 gene disrupted were obtained, and showed about 40% reduction of total xylanase activity in comparison to the wild type when grown in culture with xylan as carbon source. Even if the FGSG_03624 xylanase is able to induce hypersensitive-like symptoms on a monocot plant, FGSG_03624 gene deletion mutants were fully virulent on wheat cvs. Bobwhite and Nandu, probably because of xylanase gene redundancy. Therefore the role of this xylanase during wheat infection remains elusive. To get insight about the importance of xylanase activities produced by the pathogen during infection of host plants, Xyr1, a transcriptional regulator factor putatively regulating the expression of several xylanase genes has been deleted by targeted homologous recombination. Deleted mutants of the FGSG_17662 gene, encoding Xyr1, were heavily impaired both in total secreted xylanase activity and in fungal biomass formation when grown in liquid culture with xylan as sole carbon source. In comparison to WT, the fungal dry weight was reduced, by 40% to 70% and the total xylanase activity was reduced by about 90%. F. graminearum Xyr1 deletion mutants are now available to be submitted to expression analysis in vivo to verify the Xyr1 mediated regulation of the expression of genes encoding for xylanolitic enzymes during plant infection. The Xyr1 disrupted mutants will be characterized for their virulence by inoculating Triticum aestivum spikes. If these mutants will be verified as impaired in virulence, in planta overexpression of xylanase inhibitors may be considered as a new tool to control FHB
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".