Survey of maize differential expression upon environmental exposure to the tar spot pathogen Phyllahcora maydis

Tar spot of maize, caused by Phyllachora maydis, is an emerging threat to crop production across the United States and Canada. Current effective management of the disease includes application of fungicides and use of partially resistant maize varieties. Several studies have focused on mapping of tar spot resistant loci from maize diversity panels. However, no additional analyses have been reported to further our understanding of the maize defense response to P. maydis. Therefore, prior to the availability of inoculation procedures, we performed transcriptome sequencing from maize leaf tissue exposed to P. maydis from a tar spot infested field and assessed differential gene transcript expression. Over the course of disease development, leaves were sampled at two timepoints: 10 days and 24 days post-exposure. Differentially expressed genes (DEGs) were determined by comparing gene transcript expression of the exposed samples to non-exposed controls at the respective timepoints. RNAseq of maize cv. B73 after environmental exposure to a high inoculum load of Phyllachora maydis in an infested field. Plants were exposed for a 10 days in the field. then brought back to the greenhouse. A subset of plants were not placed in the field (non-exposed). Samples were collected at two times during the experiment 10 days and 24 days after the start of the exposure.