Project description:The maize smut fungus, Sporisorium reilianum f. sp. zeae, which is an important biotrophic pathogen responsible for extensive crop losses, infects maize by invading the root during the early seedling stage. In order to investigate disease-resistance mechanisms at this early seedling stage, digital gene expression (DGE) analysis, which applies a dual-enzyme approach (DpnII and NlaIII), was used to identify the transcriptional changes in roots of Huangzao4 (susceptible) and Mo17 (resistant) after inoculation with teliospores of S. reilianum. Before and after inoculation, pathogenesis-related genes were differentially regulated and enzymes involved in controlling reactive oxygen species (ROS) levels showed different activity between Huangzao4 and Mo17, which can potentially lead to changes in the growth of S. reilianum and ROS production in maize. Moreover, lignin depositions of roots were also changed differentially during root colonization of hyphae between Huangzao4 and Mo17. These results suggest that the interplays between S. reilianum and maize during the early infection stage involve many interesting transcriptional and physiological changes, which offer several novel insights for understanding the mechanisms of resistance to the fungal infection. Examination of control stage (ck), post-inoculation stage1 (P1) and post-inoculation stage2 (P2) in Huangzao4 (susceptible) and Mo17 (resistant)
Project description:The maize smut fungus, Sporisorium reilianum f. sp. zeae, which is an important biotrophic pathogen responsible for extensive crop losses, infects maize by invading the root during the early seedling stage. In order to investigate disease-resistance mechanisms at this early seedling stage, digital gene expression (DGE) analysis, which applies a dual-enzyme approach (DpnII and NlaIII), was used to identify the transcriptional changes in roots of Huangzao4 (susceptible) and Mo17 (resistant) after inoculation with teliospores of S. reilianum. Before and after inoculation, pathogenesis-related genes were differentially regulated and enzymes involved in controlling reactive oxygen species (ROS) levels showed different activity between Huangzao4 and Mo17, which can potentially lead to changes in the growth of S. reilianum and ROS production in maize. Moreover, lignin depositions of roots were also changed differentially during root colonization of hyphae between Huangzao4 and Mo17. These results suggest that the interplays between S. reilianum and maize during the early infection stage involve many interesting transcriptional and physiological changes, which offer several novel insights for understanding the mechanisms of resistance to the fungal infection.
Project description:Head smut of maize, which is caused by the Sporisorium reilianum f. sp. Zeae (Kühn), has been a serious disease in maize. In order to find head smut resistant candidate genes, microarrays were used to monitor the gene expression profiles between disease resistant near isogenic lines (NIL) L282 and L43, highly resistant inbred line Q319 and highly susceptible inbred line Huangzao4 after 0 to7 days post inoculation of S.reiliana by artificial inoculation method.
Project description:The maize smut fungi Ustilago maydis and Sporisorium reilianum are closely related and have similar genomes in terms of size and synteny. While U. maydis induces tumors locally at sites of infection, S. reilianum systemically colonizes the host and causes symptoms in the inflorescences. To investigate the genetic basis of these differences, an interspecific recombinant hybrid (rUSH) with the mating type system of S. reilianum was generated. rUSH exhibited extensive in-planta proliferation, showing a S. reilianum-like phenotype at all developmental stages except teliospore formation. Transcriptome profiling revealed that expression of pathogenicity-related effector gene orthologs was induced in rUSH, but not in a wild-type hybrid control. Multiple transcriptome comparisons identified 253 differentially expressed one-to-one effector orthologs with distinct regulatory patterns, including cis-, trans-, and rUSH-specific regulation. Functional analysis via CRISPR/Cas9 mutagenesis uncovered three novel virulence factors among the rUSH-specific regulated effectors. Ultimately, rUSH facilitated to identify the transcription factor UmHdp2 as key regulator of U. maydis-induced tumorigenesis. Together, these findings highlight the utility of a recombinant, interspecific hybrid in unraveling the molecular mechanisms underlying pathogenic differences in closely related fungal pathogens.
Project description:The maize smut fungi Ustilago maydis and Sporisorium reilianum are closely related and have similar genomes in terms of size and synteny. While U. maydis induces tumors locally at sites of infection, S. reilianum systemically colonizes the host and causes symptoms in the inflorescences. To investigate the genetic basis of these differences, an interspecific recombinant hybrid (rUSH) with the mating type system of S. reilianum was generated. rUSH exhibited extensive in-planta proliferation, showing a S. reilianum-like phenotype at all developmental stages except teliospore formation. Transcriptome profiling revealed that expression of pathogenicity-related effector gene orthologs was induced in rUSH, but not in a wild-type hybrid control. Multiple transcriptome comparisons identified 253 differentially expressed one-to-one effector orthologs with distinct regulatory patterns, including cis-, trans-, and rUSH-specific regulation. Functional analysis via CRISPR/Cas9 mutagenesis uncovered three novel virulence factors among the rUSH-specific regulated effectors. Ultimately, rUSH facilitated to identify the transcription factor UmHdp2 as key regulator of U. maydis-induced tumorigenesis. Together, these findings highlight the utility of a recombinant, interspecific hybrid in unraveling the molecular mechanisms underlying pathogenic differences in closely related fungal pathogens.
Project description:Sporisorium reilianum f. sp. zeae is an important biotrophic pathogen that causes head smut disease in maize. Head smut is not obvious until the tassels and ears emerge. S. reilianum has a very long life cycle that spans almost the entire developmental program of maize after the pathogen successfully invades the root. The aim of this study was to understand at a molecular level how this pathogen interacts with the host during its long life cycle, and how this interaction differs between susceptible and resistant varieties of maize after hyphal invasion. We investigated transcriptional changes in the resistant maize line Mo17 at four developmental stages using a maize 70mer-oligonucleotide microarray. We found that there was a lengthy compatible relationship between the pathogen and host until the early 8th-leaf stage. The resistance in Mo17 relied on the assignment of auxins and regulation of flavonoids in the early floral primordium during the early floral transition stage. We propose a model describing the putative mechanism of head smut resistance in Mo17 during floral transition. In the model, the synergistic regulations among auxins, flavonoids, and hyphal growth play a key role in maintaining compatibility with S. reilianum in the resistant maize line After inoculation using the hyphae of S. reilianum, the shoot apexes of inoculated Mo17 (resistant maize line) that contained hyphae but displayed normal morphology were collected for RNA extraction at at four vegetative stages; the 2nd-, 4th-, 6th-, and 8th-leaf stages. RNA samples from mock-inoculated and inocultated Mo17 were hybridized to the 46K maize 70-mer oligonucleotide microarray. Hybridization was performed in three biological replicates with Cy5/Cy3 dye swap as technical replicates.
Project description:Head smut of maize, which is caused by the Sporisorium reilianum f. sp. Zeae (Kühn), has been a serious disease in maize. In order to find head smut resistant candidate genes, microarrays were used to monitor the gene expression profiles between disease resistant near isogenic lines (NIL) L282 and L43, highly resistant inbred line Q319 and highly susceptible inbred line Huangzao4 after 0 to7 days post inoculation of S.reiliana by artificial inoculation method. Maize leaves were selected at 0d, 1d, 2d, 4d, 7d post inoculation for RNA extraction and hybridization on Affymetrix microarrays. We sought to obtain different expression genes of different varieties at each inoculation stage in order to find head smut resistant candidate genes.