Characterization of MoLDB1 Required for Vegetative Growth, Infection-Related Morphogenesis, and Pathogenicity in the Rice Blast Fungus Magnaporthe oryzae

• Published in: Molecular plant-microbe interactions Vol. 23; no. 10; pp. 1260 - 1274
• Main Authors: Li, Ya, Liang, Shen, Yan, Xia, Wang, Hong, Li, Debao, Soanes, Darren M, Talbot, Nicholas J, Wang, Zonghua, Wang, Zhengyi
• Format: Journal Article
• Language: English
• Published: St. Paul, MN APS Press 01.10.2010; The American Phytopathological Society
• Subjects: Amino Acid Sequence; amino acid sequences; appressoria; asexual reproduction; binding sites; Biological and medical sciences; blast disease; cell nucleus; cell wall components; conidia; cytochemistry; Down-Regulation; Fundamental and applied biological sciences. Psychology; Fungal plant pathogens; fungal proteins; Fungal Proteins - genetics; Fungal Proteins - metabolism; fungal spores; gene expression; Gene Expression Regulation, Fungal; hydrophobicity; Magnaporthe; Magnaporthe - genetics; Magnaporthe - pathogenicity; Magnaporthe oryzae; Molecular Sequence Data; morphogenesis; Mutagenesis, Insertional; mutants; Mutation; Oryza - microbiology; Oryza sativa; pathogenicity; Phenotype; Phylogeny; Phytopathology. Animal pests. Plant and forest protection; Plant Diseases - microbiology; plant pathogenic fungi; sexual reproduction; Ascomycota; Fungi; Morphogenesis; Pathogenicity; Oryza sativa; Monocotyledones; Plant pathogen; Gramineae; Angiospermae; Magnaporthe oryzae; Spermatophyta; Cereal crop
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI-03-10-0052

An insertional mutagenesis screen in the rice blast fungus, Magnaporthe oryzae, identified a novel mutant, A2-12-3, which is defective in infection-related morphogenesis and pathogenicity. Analysis of the mutation confirmed an insertion into MoLDB1, which putatively encodes an 806-amino-acid protein with a predicted LIM binding domain. Targeted gene deletion mutants of MoLDB1 were unable to produce asexual or sexual spores and were significantly impaired in vegetative growth and fungal virulence. The Δmoldb1 mutants also showed reduced expression of genes coding hydrophobic proteins (e.g. MPG1 and MHP1), resulting in an easily wettable phenotype in vegetative culture. Moreover, the expression of four genes encoding LIM proteins predicted from the M. oryzae genome was significantly downregulated by deletion of MoLDB1. Analysis of an M. oryzae strain expressing a MoLbd1-green fluorescent protein gene fusion was consistent with the protein being nuclear localized. When considered together, MoLdb1 appears to be involved in regulation of cell wall proteins, including hydrophobins and LIM proteins, and is essential for conidiation, sexual development, appressorium formation, and pathogenicity in M. oryzae.