Genome and secretome analysis of the hemibiotrophic fungal pathogen, Moniliophthoraroreri, which causes frosty pod rot disease of cacao: mechanisms of the biotrophic and necrotrophic phases

Author(s):Show less -

Meinhardt, Lyndel W. ^[1] ; Lacerda Costa, Gustavo Gilson ^[2] ; Thomazella, Daniela P. T. ^[3] ; Teixeira, Paulo Jose P. L. ^[3] ; Carazzolle, Marcelo Falsarella ^[2] ; Schuster, Stephan C. ^[4] ; Carlson, John E. ^[5] ; Guiltinan, Mark J. ^[6] ; Mieczkowski, Piotr ^[7] ; Farmer, Andrew ^[8] ; Ramaraj, Thiruvarangan ^[8] ; Crozier, Jayne ^[9] ; Davis, Robert E. ^[10] ; Shao, Jonathan ^[10] ; Melnick, Rachel L. ^[1] ; Pereira, Goncalo A. G. ^[3] ; Bailey, Bryan A. ^[1]

Affiliation

^[1] ARS, Sustainable Perennial Crops Lab, USDA, Beltsville, MD 20705 - USA

^[2] Univ Estadual Campinas, Ctr Nacl Proc Alto Desempenho Sao Paulo, BR-13083970 Campinas, SP - Brazil

^[3] Univ Estadual Campinas, UNICAMP, Inst Biol, Dept Genet Evolucao & Bioagentes, Lab Genom & Expr, BR-13083970 Campinas, SP - Brazil

^[4] Penn State Univ, Ctr Infect Dis Dynam, University Pk, PA 16802 - USA

^[5] Penn State Univ, Dept Ecosyst Sci & Management, University Pk, PA 16802 - USA

^[6] Penn State Univ, Dept Hort, University Pk, PA 16802 - USA

^[7] Univ N Carolina, Sch Med, Dept Genet, Chapel Hill, NC 27599 - USA

^[8] Natl Ctr Genom Res, Santa Fe, NM 87505 - USA

^[9] CABI Biosci UK Ctr, Egham, Surrey - England

^[10] ARS, Mol Plant Pathol Lab, USDA, Beltsville, MD 20705 - USA

• Document type: Journal article
• Source: BMC Genomics; v. 15, FEB 27 2014.
• Web of Science Citations: 40

Abstract

Background: The basidiomycete Moniliophthora roreri is the causal agent of Frosty pod rot (FPR) disease of cacao (Theobroma cacao), the source of chocolate, and FPR is one of the most destructive diseases of this important perennial crop in the Americas. This hemibiotroph infects only cacao pods and has an extended biotrophic phase lasting up to sixty days, culminating in plant necrosis and sporulation of the fungus without the formation of a basidiocarp. Results: We sequenced and assembled 52.3 Mb into 3,298 contigs that represent the M. roreri genome. Of the 17,920 predicted open reading frames (OFRs), 13,760 were validated by RNA-Seq. Using read count data from RNA sequencing of cacao pods at 30 and 60 days post infection, differential gene expression was estimated for the biotrophic and necrotrophic phases of this plant-pathogen interaction. The sequencing data were used to develop a genome based secretome for the infected pods. Of the 1,535 genes encoding putative secreted proteins, 1,355 were expressed in the biotrophic and necrotrophic phases. Analysis of the data revealed secretome gene expression that correlated with infection and intercellular growth in the biotrophic phase and invasive growth and plant cellular death in the necrotrophic phase. Conclusions: Genome sequencing and RNA-Seq was used to determine and validate the Moniliophthora roreri genome and secretome. High sequence identity between Moniliophthora roreri genes and Moniliophthora perniciosa genes supports the taxonomic relationship with Moniliophthora perniciosa and the relatedness of this fungus to other basidiomycetes. Analysis of RNA-Seq data from infected plant tissues revealed differentially expressed genes in the biotrophic and necrotrophic phases. The secreted protein genes that were upregulated in the biotrophic phase are primarily associated with breakdown of the intercellular matrix and modification of the fungal mycelia, possibly to mask the fungus from plant defenses. Based on the transcriptome data, the upregulated secreted proteins in the necrotrophic phase are hypothesized to be actively attacking the plant cell walls and plant cellular components resulting in necrosis. These genes are being used to develop a new understanding of how this disease interaction progresses and to identify potential targets to reduce the impact of this devastating disease. (AU)

• FAPESP's process: 13/08293-7 - CCES - Center for Computational Engineering and Sciences
• Grantee: Munir Salomao Skaf
• Support Opportunities: Research Grants - Research, Innovation and Dissemination Centers - RIDC