title: Transcriptomic changes in the plant pathogenic fungus Rhizoctonia solani AG-3 in response to the antagonistic bacteria Serratia proteamaculans and Serratia plymuthica.
abstract: BACKGROUND
  Improved understanding of bacterial-fungal interactions in the rhizosphere should assist in the successful application of bacteria as biological control agents against fungal pathogens of plants, providing alternatives to chemicals in sustainable agriculture. Rhizoctonia solani is an important soil-associated fungal pathogen and its chemical treatment is not feasible or economic. The genomes of the plant-associated bacteria Serratia proteamaculans S4 and Serratia plymuthica AS13 have been sequenced, revealing genetic traits that may explain their diverse plant growth promoting activities and antagonistic interactions with R. solani. To understand the functional response of this pathogen to different bacteria and to elucidate whether the molecular mechanisms that the fungus exploits involve general stress or more specific responses, we performed a global transcriptome profiling of R. solani Rhs1AP anastomosis group 3 (AG-3) during interaction with the S4 and AS13 species of Serratia using RNA-seq.
  
  
  RESULTS
  Approximately 104,504 million clean 75-100 bp paired-end reads were obtained from three libraries, each in triplicate (AG3-Control, AG3-S4 and AG3-AS13). Transcriptome analysis revealed that approximately 10% of the fungal transcriptome was differentially expressed during challenge with Serratia. The numbers of S4- and AS13-specific differentially expressed genes (DEG) were 866 and 292 respectively, while there were 1035 common DEGs in the two treatment groups. Four hundred and sixty and 242 genes respectively had values of log2 fold-change > 3 and for further analyses this cut-off value was used. Functional classification of DEGs based on Gene Ontology enrichment analysis and on KEGG pathway annotations revealed a general shift in fungal gene expression in which genes related to xenobiotic degradation, toxin and antioxidant production, energy, carbohydrate and lipid metabolism and hyphal rearrangements were subjected to transcriptional regulation.
  
  
  CONCLUSIONS
  This RNA-seq profiling generated a novel dataset describing the functional response of the phytopathogen R. solani AG3 to the plant-associated Serratia bacteria S4 and AS13. Most genes were regulated in the same way in the presence of both bacterial isolates, but there were also some strain-specific responses. The findings in this study will be beneficial for further research on biological control and in depth exploration of bacterial-fungal interactions in the rhizosphere.
authors: Department of Forest Mycology and Plant Pathology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Box 7026, SE-75007, Uppsala, Sweden. konstantia.gkarmiri@slu.se.
authors: Konstantia
authors: K
authors: Gkarmiri
authors: Department of Forest Mycology and Plant Pathology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Box 7026, SE-75007, Uppsala, Sweden. roger.finlay@slu.se.
authors: Roger D
authors: RD
authors: Finlay
authors: Department of Forest Mycology and Plant Pathology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Box 7026, SE-75007, Uppsala, Sweden. sadhna.alstrom@slu.se.
authors: Sadhna
authors: S
authors: Alström
authors: Department of Plant Pathology, Center for Integrated Fungal Research, Fungal Disease Ecology, Genetics and Population Biology, North Carolina State University, 851 Main Campus Drive, Suite 233, 225 Partners III, Raleigh, NC, 27606, USA. ethomas@ncsu.edu.
authors: Elizabeth
authors: E
authors: Thomas
authors: Department of Plant Pathology, Center for Integrated Fungal Research, Fungal Disease Ecology, Genetics and Population Biology, North Carolina State University, 851 Main Campus Drive, Suite 233, 225 Partners III, Raleigh, NC, 27606, USA. marc_cubeta@ncsu.edu.
authors: Marc A
authors: MA
authors: Cubeta
authors: Department of Forest Mycology and Plant Pathology, Uppsala BioCenter, Swedish University of Agricultural Sciences, Box 7026, SE-75007, Uppsala, Sweden. nils.hogberg@slu.se.
authors: Nils
authors: N
authors: Högberg
mesh_terms: D000898:Antibiosis; D005656:Fungal Proteins / Q000235:genetics*; D020869:Gene Expression Profiling / Q000379:methods*; D015966:Gene Expression Regulation, Fungal; D063990:Gene Ontology; D012331:RNA, Fungal / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D012232:Rhizoctonia / Q000235:genetics* / Q000502:physiology; D058441:Rhizosphere; D017423:Sequence Analysis, RNA / Q000379:methods*; D012705:Serratia / Q000502:physiology*; D013045:Species Specificity
chemical_list: D005656:Fungal Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger