Dataset Information

UvHOG1 is important for hyphal growth and stress responses in the rice false smut fungus Ustilaginoidea virens.

ABSTRACT: Rice false smut caused by Ustilaginoidea virens is one of the most important diseases of rice worldwide. Although its genome has been sequenced, to date there is no report on targeted gene deletion in U. virens and no molecular studies on genetic mechanisms regulating the infection processes of this destructive pathogen. In this study, we attempted to generate knockout mutants of the ortholog of yeast HOG1 MAP kinase gene in U. virens. One Uvhog1 deletion mutant was identified after screening over 600 hygromycin-resistant transformants generated by Agrobacterium tumefaciens mediated transformation. The Uvhog1 mutant was reduced in growth rate and conidiation but had increased sensitivities to SDS, Congo red, and hyperosmotic stress. Deletion of UvHOG1 resulted in reduced expression of the stress response-related genes UvATF1 and UvSKN7. In the Uvhog1 mutant, NaCl treatment failed to stimulate the accumulation of sorbitol and glycerol. In addition, the Uvhog1 mutant had reduced toxicity on shoot growth in rice seed germination assays. Overall, as the first report of targeted gene deletion mutant in U. virens, our results showed that UvHOG1 likely has conserved roles in regulating stress responses, hyphal growth, and possibly secondary metabolism.

SUBMITTER: Zheng D

PROVIDER: S-EPMC4837404 | biostudies-literature | 2016 Apr

REPOSITORIES: biostudies-literature

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UvHOG1 is important for hyphal growth and stress responses in the rice false smut fungus Ustilaginoidea virens.

Zheng Dawei D Wang Yi Y Han Yu Y Xu Jin-Rong JR Wang Chenfang C

Scientific reports 20160420

Rice false smut caused by Ustilaginoidea virens is one of the most important diseases of rice worldwide. Although its genome has been sequenced, to date there is no report on targeted gene deletion in U. virens and no molecular studies on genetic mechanisms regulating the infection processes of this destructive pathogen. In this study, we attempted to generate knockout mutants of the ortholog of yeast HOG1 MAP kinase gene in U. virens. One Uvhog1 deletion mutant was identified after screening ov ...[more]

PMID: 27095476

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Project description:Rice false smut caused by Ustilaginoidea virens is a destructive disease in rice cropping areas of the world. The present study is focused on the morphology, pathogenicity, mating-type loci distribution, and genetic characterization of different isolates of U. virens. A total of 221 strains of U. virens were collected from 13 rice-growing regions in southwest China. The morphological features of these strains exhibited high diversity, and the pathogenicity of the smut fungus showed significant differentiation. There was no correlation between pathogenicity and sporulation. Mating-type locus (MAT) analysis revealed that all 221 isolates comprised heterothallic and homothallic forms, wherein 204 (92.31%) and 17 (7.69%) isolates belonged to heterothallic and homothallic mating types, respectively. Among 204 strains of heterothallic mating types, 62 (28.05%) contained MAT1-1-1 idiomorphs, and 142 isolates (64.25%) had the MAT1-2-1 idiomorph. Interestingly, strains isolated from the same fungus ball had different mating types. The genetic structure of the isolates was analyzed using simple sequence repeats (SSRs) and single-nucleotide polymorphisms (SNPs). All isolates were clustered into five genetic groups. The values of Nei's gene diversity (H) and Shannon's information index (I) indicated that all strains as a group had higher genetic diversity than strains from a single geographical population. The pairwise population fixation index (FST) values also indicated significant genetic differentiation among all compared geographical populations. The analysis of molecular variation (AMOVA) indicated greater genetic variation within individual populations and less genetic variation among populations. The results showed that most of the strains were not clustered according to their geographical origin, showing the rich genetic diversity and the complex and diverse genetic background of U. virens in southwest China. These results should help to better understand the biological and genetic diversity of U. virens in southwest China and provide a theoretical basis for building effective management strategies.

Project description:Rice false smut, caused by the fungal pathogen Ustilaginoidea virens, is a worldwide rice fungal disease. However, the molecular mechanism of the pathogenicity of the fungus U. virens remains unclear. To understand the molecular mechanism of pathogenesis of the fungus U. virens, we performed an integrated analysis of the transcriptome and metabolome of strongly (S) and weakly (W) virulent strains both before and after the infection of panicles. A total of 7932 differential expressed genes (DEGs) were identified using transcriptome analysis. Gene ontology (GO) and metabolic pathway enrichment analysis indicated that amino acid metabolism, autophagy-yeast, MAPK signaling pathway-yeast, and starch and sucrose metabolism were closely related to the pathogenicity of U. virens. Genes related to pathogenicity were significantly upregulated in the strongly virulent strain, and were ATG, MAPK, STE, TPS, and NTH genes. However, genes involved in the negative regulation of pathogenesis were significantly downregulated and contained TOR kinase, TORC1, and autophagy-related protein genes. Metabolome analysis identified 698 differentially accumulated metabolites (DAMs), including 13 categories of organic acids and derivatives, lipids and lipid-like molecules, organoheterocyclic compounds. The significantly enriched pathways of DAMs mainly included amino acids and carbohydrates, and they accumulated after infection by the S strain. To understand the relevance of DEGs and DAMs in the pathogenicity of U. virens, transcriptomic and metabolomic data were integrated and analyzed. These results further confirmed that the pathogenesis of U. virens was regulated by DEGs and DAMs related to these four pathways, involving arginine and proline metabolism, lysine biosynthesis, alanine, aspartate and glutamate metabolism, and starch and sugar metabolism. Therefore, we speculate that the pathogenicity of U. virens is closely related to the accumulation of amino acids and carbohydrates, and to the changes in the expression of related genes.

Project description:BACKGROUND: Rice false smut caused by Villosiclava virens is a devastating fungal disease that spreads in major rice-growing regions throughout the world. However, the genomic information for this fungal pathogen is limited and the pathogenic mechanism of this disease is still not clear. To facilitate genetic, molecular and genomic studies of this fungal pathogen, we constructed the first BAC-based physical map and performed the first genome survey for this species. RESULTS: High molecular weight genomic DNA was isolated from young mycelia of the Villosiclava virens strain UV-8b and a high-quality, large-insert and deep-coverage Bacterial Artificial Chromosome (BAC) library was constructed with the restriction enzyme HindIII. The BAC library consisted of 5,760 clones, which covers 22.7-fold of the UV-8b genome, with an average insert size of 140 kb and an empty clone rate of lower than 1%. BAC fingerprinting generated successful fingerprints for 2,290 BAC clones. Using the fingerprints, a whole genome-wide BAC physical map was constructed that contained 194 contigs (2,035 clones) spanning 51.2 Mb in physical length. Bidirectional-end sequencing of 4,512 BAC clones generated 6,560 high quality BAC end sequences (BESs), with a total length of 3,030,658 bp, representing 8.54% of the genome sequence. Analysis of the BESs revealed general genome information, including 51.52% GC content, 22.51% repetitive sequences, 376.12/Mb simple sequence repeat (SSR) density and approximately 36.01% coding regions. Sequence comparisons to other available fungal genome sequences through BESs showed high similarities to Metarhizium anisopliae, Trichoderma reesei, Nectria haematococca and Cordyceps militaris, which were generally in agreement with the 18S rRNA gene analysis results. CONCLUSION: This study provides the first BAC-based physical map and genome information for the important rice fungal pathogen Villosiclava virens. The BAC clones, physical map and genome information will serve as fundamental resources to accelerate the genetic, molecular and genomic studies of this pathogen, including positional cloning, comparative genomic analysis and whole genome sequencing. The BAC library and physical map have been opened to researchers as public genomic resources (http://gresource.hzau.edu.cn/resource/resource.html).

Dataset Information

UvHOG1 is important for hyphal growth and stress responses in the rice false smut fungus Ustilaginoidea virens.

Publications

UvHOG1 is important for hyphal growth and stress responses in the rice false smut fungus Ustilaginoidea virens.

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