title: Genomes and transcriptomes of partners in plant-fungal-interactions between canola (Brassica napus) and two Leptosphaeria species.
abstract: Leptosphaeria maculans 'brassicae' is a damaging fungal pathogen of canola (Brassica napus), causing lesions on cotyledons and leaves, and cankers on the lower stem. A related species, L. biglobosa 'canadensis', colonises cotyledons but causes few stem cankers. We describe the complement of genes encoding carbohydrate-active enzymes (CAZys) and peptidases of these fungi, as well as of four related plant pathogens. We also report dual-organism RNA-seq transcriptomes of these two Leptosphaeria species and B. napus during disease. During the first seven days of infection L. biglobosa 'canadensis', a necrotroph, expressed more cell wall degrading genes than L. maculans 'brassicae', a hemi-biotroph. L. maculans 'brassicae' expressed many genes in the Carbohydrate Binding Module class of CAZy, particularly CBM50 genes, with potential roles in the evasion of basal innate immunity in the host plant. At this time, three avirulence genes were amongst the top 20 most highly upregulated L. maculans 'brassicae' genes in planta. The two fungi had a similar number of peptidase genes, and trypsin was transcribed at high levels by both fungi early in infection. L. biglobosa 'canadensis' infection activated the jasmonic acid and salicylic acid defence pathways in B. napus, consistent with defence against necrotrophs. L. maculans 'brassicae' triggered a high level of expression of isochorismate synthase 1, a reporter for salicylic acid signalling. L. biglobosa 'canadensis' infection triggered coordinated shutdown of photosynthesis genes, and a concomitant increase in transcription of cell wall remodelling genes of the host plant. Expression of particular classes of CAZy genes and the triggering of host defence and particular metabolic pathways are consistent with the necrotrophic lifestyle of L. biglobosa 'canadensis', and the hemibiotrophic life style of L. maculans 'brassicae'.
authors: School of Botany, The University of Melbourne, Parkville, Victoria, Australia.
authors: Rohan G T
authors: RG
authors: Lowe
authors: ARC Centre of Excellence in Plant Cell Walls, School of Botany, The University of Melbourne, Parkville, Victoria, Australia.
authors: Andrew
authors: A
authors: Cassin
authors: INRA-Bioger, UR1290, Thiverval-Grignon, France.
authors: Jonathan
authors: J
authors: Grandaubert
authors: School of Botany, The University of Melbourne, Parkville, Victoria, Australia.
authors: Bethany L
authors: BL
authors: Clark
authors: School of Botany, The University of Melbourne, Parkville, Victoria, Australia.
authors: Angela P
authors: AP
authors: Van de Wouw
authors: INRA-Bioger, UR1290, Thiverval-Grignon, France.
authors: Thierry
authors: T
authors: Rouxel
authors: School of Botany, The University of Melbourne, Parkville, Victoria, Australia.
authors: Barbara J
authors: BJ
authors: Howlett
mesh_terms: D001203:Ascomycota / Q000235:genetics*; D029688:Brassica napus / Q000235:genetics* / Q000382:microbiology*; D016000:Cluster Analysis; D018548:Cotyledon / Q000235:genetics / Q000382:microbiology; D015966:Gene Expression Regulation, Fungal; D018506:Gene Expression Regulation, Plant; D016681:Genome, Fungal; D018745:Genome, Plant; D023281:Genomics; D054884:Host-Pathogen Interactions / Q000235:genetics*; D010447:Peptide Hydrolases / Q000737:chemistry / Q000235:genetics; D010641:Phenotype; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D059467:Transcriptome
chemical_list: D010447:Peptide Hydrolases