Uncovering temporal gene expression profiles of the yellow rust pathogen during infection of wheat
M. ELMORE (1), C. Conley (2), B. Perroud (1), L. Froenicke (1), J. Peng (2), X. Wang (3), J. Dubcovsky (3), R. Michelmore (3) (1) Genome Center, University of California at Davis, U.S.A.; (2) Department of Statistics, University of California at Davis, U.S.A.; (3) Department of Plant Science, , University of California at Davis, U.S.A.

Yellow (stripe) rust, caused by the obligate biotrophic pathogen Puccinia striiformis f. sp. tritici (PST) is one of the most destructive foliar fungal diseases of wheat worldwide. To investigate molecular PST-wheat interactions, we generated strand-specific cDNA libraries to identify PST genes expressed 5, 8, 15 and 22 days post inoculation (dpi) in susceptible wheat. De novo assembly of over 279 million paired-end PST-specific reads resulted in 25,518 unique rust transcripts. Expression analysis identified 36 differentially regulated PST gene clusters throughout the course of infection. Many clusters were enriched with genes encoding proteins known to be expressed in haustoria, germinated spores, and/or predicted to be secreted. Haustoria-expressed secreted proteins such as esterase-like enzymes, proteases, carbohydrate active enzymes (CAZymes), and cupredoxin were highly expressed at 8 and 15 dpi, supporting a role in fungal virulence and nutrient acquisition during biotrophic growth. Genes encoding fungal cell wall proteins were predominantly expressed during sporulation (15 and 22 dpi). Ergosterol biosynthetic genes vital for fungal membrane maintenance were constitutively expressed during infection. Our results provide new insights into the molecular events during PST infection and identify candidate targets for inhibiting growth and reproduction of the pathogen. This may lead to new avenues for durable disease resistance in wheat through host-induced gene silencing.

Abstract Number: P11-353
Session Type: Poster