Condition-dependent co-regulation of genomic clusters of virulence factors in the grapevine trunk pathogen Neofusicoccum parvum.
The ascomycete Neofusicoccum parvum, one of the causal agents of Botryosphaeria dieback, is a destructive wood-infecting fungus and a serious threat to grape production worldwide. The capability to colonize woody tissue, combined with the secretion of phytotoxic compounds, is thought to underlie its pathogenicity and virulence. Here, we describe the repertoire of virulence factors and their transcriptional dynamics as the fungus feeds on different substrates and colonizes the woody stem. We assembled and annotated a highly contiguous genome using single-molecule real-time DNA sequencing. Transcriptome profiling by RNA sequencing determined the genome-wide patterns of expression of virulence factors both in vitro (potato dextrose agar or medium amended with grape wood as substrate) and in planta. Pairwise statistical testing of differential expression, followed by co-expression network analysis, revealed that physically clustered genes coding for putative virulence functions were induced depending on the substrate or stage of plant infection. Co-expressed gene clusters were significantly enriched not only in genes associated with secondary metabolism, but also in those associated with cell wall degradation, suggesting that dynamic co-regulation of transcriptional networks contributes to multiple aspects of N. parvum virulence. In most of the co-expressed clusters, all genes shared at least a common motif in their promoter region, indicative of co-regulation by the same transcription factor. Co-expression analysis also identified chromatin regulators with correlated expression with inducible clusters of virulence factors, suggesting a complex, multi-layered regulation of the virulence repertoire of N. parvum.
Department of Viticulture and Enology, University of California Davis, Davis, CA, 95616, USA.
Mélanie
M
Massonnet
Department of Viticulture and Enology, University of California Davis, Davis, CA, 95616, USA.
Abraham
A
Morales-Cruz
Department of Viticulture and Enology, University of California Davis, Davis, CA, 95616, USA.
Rosa
R
Figueroa-Balderas
Department of Plant Pathology, University of California Davis, Davis, CA, 95616, USA.
Daniel P
DP
Lawrence
US Department of Agriculture - Agricultural Research Service, Crops Pathology and Genetics Research Unit, Davis, CA, 95616, USA.
Kendra
K
Baumgartner
Department of Viticulture and Enology, University of California Davis, Davis, CA, 95616, USA.
Dario
0000-0002-4858-1508
D
Cantu
D001203:Ascomycota / Q000235:genetics*; D004270:DNA, Circular / Q000235:genetics; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D053263:Gene Regulatory Networks; D005800:Genes, Fungal; D016681:Genome, Fungal; D058977:Molecular Sequence Annotation; D005810:Multigene Family; D010935:Plant Diseases / Q000382:microbiology*; D018547:Plant Stems / Q000382:microbiology; D017422:Sequence Analysis, DNA; D017423:Sequence Analysis, RNA; D014158:Transcription, Genetic; D014774:Virulence / Q000235:genetics; D037521:Virulence Factors / Q000235:genetics*; D027843:Vitis / Q000382:microbiology*; D014934:Wood / Q000382:microbiology
D004270:DNA, Circular; D037521:Virulence Factors
Botryosphaeria dieback; CAZymes; RNA-seq; cell wall degradation; secondary metabolism; single-molecule real-time (SMRT) sequencing; weighted co-expression network analysis