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

October 2010 , Volume 23 , Number  10
Pages  1,260 - 1,274

Ya Li,1 Shen Liang,1 Xia Yan,1 Hong Wang,1 Debao Li,1 Darren M. Soanes,2 Nicholas J. Talbot,2 Zonghua Wang,3 and Zhengyi Wang1

1State Key Laboratory for Rice Biology, Institute of Biotechnology, Zhejiang University, Hangzhou 310029, People's Republic of China; 2School of Biosciences, University of Exeter, Geoffrey Pope Building, Exeter EX4 4QD, United Kingdom; 3The Key Laboratory of Biopesticide and Chemistry Biology, Ministry of Education, Fujian Agriculture and Forestry University, Fuzhou 350002, People's Republic of China

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Accepted 20 June 2010.

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.

© 2010 The American Phytopathological Society