Maize Gene Expression Profiling Reveals Susceptible Response Genes during Grey Leaf Spot Fungus Cercospora zeina Infection

Cercospora zeina is the major casual agent of the widespread and destructive maize grey leaf spot disease in South Africa. Currently there is no completely susceptible maize line available. Little is known about the underlying molecular dialogue between the host and the pathogen, or whether resistance of pathogenesis can be improved through breeding. In this study, we generated maize transcriptome profiles during early and late infection stages from a field trial of maize B73 line. We identified ~2,000 are differentially expressed in each condition. The maize photosynthesis pathway was largely reduced in the late infection stage due to the severe destroy of the photosynthesis components.  Maize genes that were up-regulated in response to the fungus were enriched for GO terms (AGRIGO, FDR < 0.05) representing breakdown of cellular components, namely catabolism of polysaccharides, chitin, cell wall macromolecules,  aromatic compounds, cellular nitrogen compounds, as well as carboxylic acid transport.  This may reflect the outcome of manipulation of host responses by the fungus to increase nutrient acquisition.  Additional enriched GO terms included protein amino acid phosphorylation, response to biotic stimulus, and oxidation/reduction. On the other hand, the fungus hijacked the host metabolic pathway and utilized the host carbohydrate metabolic system as their carbon source