Project description:Host-pathogen co-evolutionary dynamics force microbial plant pathogens to constantly develop and adjust specific adaptations to thrive in their plant host, and therefore also act as strong drivers of divergence and speciation in pathogens. Factors that confer host specialization and determine host specificity are very diverse and range from molecular and morphological strategies to metabolic and reproductive adaptations. Identification of these key factors is a major goal in the study of pathogen evolution and may aid the development of sustainable crops and crop protection strategies. We here took a novel experimental approach and conducted comparative microscopy and transcriptome analyses of the closely related, recently diverged fungal pathogens Zymoseptoria tritici, Z. pseudotritici, and Z. ardabiliae that establish compatible and incompatible interactions with wheat. Although infections of the incompatible species induce plant defense response during invasion of stomatal openings, we found a highly conserved early-infection program among the three species. The transcriptional programs of the three pathogens are conserved to a large extent, as only 9.2% of the 8,885 orthologous genes are significantly differentially expressed during initial infection of wheat. The genes up-regulated in the compatible pathogen reflect adaptation to growth in wheat tissue e.g., by re-programming of fungal metabolism. In contrast, genes primarily involved in counteracting cell stress and damage are strongly induced in the incompatible species. Based on the species-specific gene expression profiles, we further identified nine candidate genes encoding putative effectors and host-specificity determinants in Z. tritici. These effectors are strongly induced in the compatible species and may interfere with host immune suppression. We also identify putative necrotrophic effectors which are induced at the onset of necrotrophic growth. Together, the results presented here indicate that host specialization has involved transcriptional adaptation of a relatively small number of genes. Our findings demonstrate the potential comparative analyses of compatible and incompatible infections present for identifying traits involved in pathogen evolution and host specialization.
Project description:Many viral pathogens cycle between humans and insects. These viruses must have evolved strategies for rapid adaptation to different host environments. However, the mechanistic basis for the adaptation process remains poorly understood. To study the mosquito-human adaptation cycle, we examined changes in RNA structures of the dengue virus genome during host adaptation. Deep sequencing and RNA structure analysis, together with fitness evaluation, revealed a process of host specialization of RNA elements of the viral 3'UTR. Adaptation to mosquito or mammalian cells involved selection of different viral populations harvesting mutations in a single stem-loop structure. The host specialization of the identified RNA structure resulted in a significant viral fitness cost in the non-specialized host, posing a constraint during host switching. Sequence conservation analysis indicated that the identified host adaptable stem loop structure is duplicated in dengue and other mosquito-borne viruses. Interestingly, functional studies using recombinant viruses with single or double stem loops revealed that duplication of the RNA structure allows the virus to accommodate mutations beneficial in one host and deleterious in the other. Our findings reveal new concepts in adaptation of RNA viruses, in which host specialization of RNA structures results in high fitness in the adapted host, while RNA duplication confers robustness during host switching.
Project description:Differentially expressed kinase genes in Rhizoctonia cerealis resistant wheat lines CI12633/Shanhongmai compared with the susceptible wheat line Wenmai 6 via Agilent Wheat Gene Expression Microarray assay. Goal was to identify the kinase genes whose expression was higher in CI12633/Shanhongmai compared with the susceptible wheat line Wenmai 6
Project description:Fungal pathogens can rapidly evolve virulence towards resistant crops in agricultural ecosystems. Gains in virulence are often mediated by the mutation or deletion of a gene encoding a protein recognized by the plant immune system. However, the loci and the mechanisms of genome evolution enabling rapid virulence evolution are poorly understood. We performed genome-wide association mapping on a global collection of 106 strains of Zymoseptoria tritici, the most damaging pathogen of wheat in Europe, to identify polymorphisms linked to virulence on two wheat varieties. We found 25 distinct genomic loci associated with reproductive success of the pathogen. However, no locus was shared between the host genotypes, suggesting host specialization. The main locus associated with virulence encoded a highly expressed, small secreted protein. Population genomic analyses showed that the gain in virulence was explained by a segregating gene deletion polymorphism. The deletion was likely adaptive by preventing detection of the encoded protein. Comparative genomics of closely related species showed that the locus emerged de novo since speciation. A large cluster of transposable elements in direct proximity to the locus generated extensive rearrangements leading to multiple independent gene losses. Our study demonstrates that rapid turnover in the chromosomal structure of a pathogen can drive host specialization.
Project description:Understanding the mechanism of low temperature (LT) adaptation is crucial to the development of cold-tolerant crops. To identify the genes involved in the development of LT tolerance in the crown of hexaploid wheat we examined the global changes in genes expression during cold-treatment using the Affymetrix Wheat Genome Chip.
Project description:Eight C. sativus isolates in total with low and high virulence on wheat and barley were collected to compare differences among proteomes of isolates and analyze differentially expressed proteins (DEPs) of different virulence and pathogenic specialization using the pathway enrichment method.
Project description:We have applied whole transcriptome profiling to infer genetic determinants of pathogenicity and host specialization in Z. tritici. Our data includes RNAseq data from early infection stages of a compatible (wheat) and a non-compatible host (Brachypodium distachyon). Overall transcription of AC genes is remarkably lower than genes on core chromosomes (CC) and only 40% of the genes are transcribed. We identify 31 AC and 1069 CC genes showing plant specific expression. In addition 21 CC genes are only upregulated in wheat supporting functional relevance in host specificity. We further explore the genomic composition and distribution of unique and paralogous genes in Z. tritici focusing on the evolutionary origin of AC genes. In contrast to previous studies we show that ACs mainly encode unique genes. Phylogenetic analyses suggest that rare duplication events in the Z. tritici genome precede diversification of Zymoseptoria species and demonstrate that ACs have been maintained in the genome of Zymoseptoria over long evolutionary times. Examination of gene expression at 3 different growth condition of the wheat pathogen Z. tritici.
Project description:We have applied whole transcriptome profiling to infer genetic determinants of pathogenicity and host specialization in Z. tritici. Our data includes RNAseq data from early infection stages of a compatible (wheat) and a non-compatible host (Brachypodium distachyon). Overall transcription of AC genes is remarkably lower than genes on core chromosomes (CC) and only 40% of the genes are transcribed. We identify 31 AC and 1069 CC genes showing plant specific expression. In addition 21 CC genes are only upregulated in wheat supporting functional relevance in host specificity. We further explore the genomic composition and distribution of unique and paralogous genes in Z. tritici focusing on the evolutionary origin of AC genes. In contrast to previous studies we show that ACs mainly encode unique genes. Phylogenetic analyses suggest that rare duplication events in the Z. tritici genome precede diversification of Zymoseptoria species and demonstrate that ACs have been maintained in the genome of Zymoseptoria over long evolutionary times.
Project description:Understanding the mechanism of low temperature (LT) adaptation is crucial to the development of cold-tolerant crops. To identify the genes involved in the development of LT tolerance in the crown of hexaploid wheat we examined the global changes in genes expression during cold-treatment using the Affymetrix Wheat Genome Chip. Time-series experiment with 4 genotypes x 8 time-points X 3 biological replicates in random block design; 96 hybridizations
Project description:Differentially expressed kinase genes in Rhizoctonia cerealis resistant wheat lines CI12633/Shanhongmai compared with the susceptible wheat line Wenmai 6 via Agilent Wheat Gene Expression Microarray assay. Goal was to identify the kinase genes whose expression was higher in CI12633/Shanhongmai compared with the susceptible wheat line Wenmai 6 CI12633/Shanhongmai vs. Wenmai 6