In Planta Proteomics and Proteogenomics of the Biotrophic Barley Fungal Pathogen Blumeria graminis f. sp. hordei>

Abstract

To further our understanding of powdery mildew biology during infection, we undertook a systematic shotgun proteomics analysis of the obligate biotroph Blumeria graminis f. sp. hordei at different stages of development in the host. Moreover we used a proteogenomics approach to feed information into the annotation of the newly sequenced genome. We analyzed and compared the proteomes from three stages of development representing different functions during the plant-dependent vegetative life cycle of this fungus. We identified 441 proteins in ungerminated spores, 775 proteins in epiphytic sporulating hyphae, and 47 proteins from haustoria inside barley leaf epidermal cells and used the data to aid annotation of the B. graminis f. sp. hordei genome. We also compared the differences in the protein complement of these key stages. Although confirming some of the previously reported findings and models derived from the analysis of transcriptome dynamics, our results also suggest that the intracellular haustoria are subject to stress possibly as a result of the plant defense strategy, including the production of reactive oxygen species. In addition, a number of small haustorial proteins with a predicted N-terminal signal peptide for secretion were identified in infected tissues: these represent candidate effector proteins that may play a role in controlling host metabolism and immunity. To further our understanding of powdery mildew biology during infection, we undertook a systematic shotgun proteomics analysis of the obligate biotroph Blumeria graminis f. sp. hordei at different stages of development in the host. Moreover we used a proteogenomics approach to feed information into the annotation of the newly sequenced genome. We analyzed and compared the proteomes from three stages of development representing different functions during the plant-dependent vegetative life cycle of this fungus. We identified 441 proteins in ungerminated spores, 775 proteins in epiphytic sporulating hyphae, and 47 proteins from haustoria inside barley leaf epidermal cells and used the data to aid annotation of the B. graminis f. sp. hordei genome. We also compared the differences in the protein complement of these key stages. Although confirming some of the previously reported findings and models derived from the analysis of transcriptome dynamics, our results also suggest that the intracellular haustoria are subject to stress possibly as a result of the plant defense strategy, including the production of reactive oxygen species. In addition, a number of small haustorial proteins with a predicted N-terminal signal peptide for secretion were identified in infected tissues: these represent candidate effector proteins that may play a role in controlling host metabolism and immunity. Fungi are the most prevalent cause of disease in plants, and failure to control them results in widespread damage and severe harvest loss. In particular, the powdery mildew Blumeria graminis attacks the cereals wheat and barley, which are two of the main food crops in Western agriculture. The nature of cereal powdery mildew infection and its detrimental effect on crop health require a continual effort aimed in fighting the disease through the use of fungicides and the breeding of novel resistant varieties. Both these approaches are currently effective albeit with very significant economic and ecological impact. However, the gradual withdrawal of some fungicides driven by concerns for their environmental impact, the constant threat of the emergence of fungicide resistance, and new virulence alleles that overcome breed resistance require new tools for disease control. This will entail the development of new classes of fungicides, introgression of novel disease resistance genes, and possibly the engineering of a specific biological control through enhancement of disease tolerance and resistance. Understanding the biology and virulence of plant pathogenic fungi is essential to meet this challenge (1Marris E. Dodds P. Glover J. Hibberd J. Zhang J.H. Sayre R. Agronomy: five crop researchers who could change the world.Nature. 2008; 456: 563-568Crossref PubMed Scopus (13) Google Scholar). Powdery mildews are easily as on and and are some of the most plant a of The powdery a of the most plant 2008; PubMed Scopus Google Scholar). 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