University of Tennessee, Entomology and Plant Pathology Department Knoxville, Tennessee, United States
Abstract Text: Obligate pathosystems carry inherent analytical difficulties. Transcriptomic analyses of such systems need to disentangle between the interacting organisms. Equipped with genomic resources for Cornus florida and Erysiphe pulchra, we analyzed the dogwood powdery mildew infection process. Dataset of 394 RNAseq from 7 dogwood cultivars of varying E. pulchra resistance across 12 timepoints pre/post-infection yielded reads mapped to 6,643 genes of the pathogen and to 27,549 genes of the host. We gained insights into up/down-regulated genes at early, mid, and late stages of infection again for both: pathogen and its host. Few upregulated genes were detected at early stages in resistant dogwoods vs many in the susceptible ones. Late upregulated genes were few and transient in the resistant cultivars but many and sustained in the susceptible ones. Notable downregulated pathogen genes in the resistant dogwoods were pathogen effectors and infection related enzymes. Pathogen transcription was upregulated in the resistant dogwood cultivars. By functional annotation of the encoded proteins, exploration of such DEGs on the pathogen side enabled identification of potential additional fungicide targets for field-testing to complement the current sprays. On the plant side, analyses of cultivars with varying resistance levels illuminated what molecular mechanisms govern this trait, to potentially enhance such defenses further. Insights gained here can be exploited for related agricultural crops affected by Erysiphales: grapevine, cereals, cucurbits, or pomes.
