|PAYNE, GARY - North Carolina State University|
|OBRIAN, GREG - North Carolina State University|
|FAKHOURY, AHMAD - Southern Illinois University|
|GEISLER, MATT - Southern Illinois University|
Submitted to: Frontiers in Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/4/2016
Publication Date: 11/21/2016
Citation: Musungu, B.M., Bhatnagar, D., Brown, R.L., Payne, G.A., Obrian, G., Fakhoury, A., Geisler, M. 2016. A network approach of gene co-expression in the zea mays/Aspergillus flavus pathosystem to map host/pathogen interaction pathways. Frontiers in Genetics. 7(206):doi.10.3389.
Interpretive Summary: Zea mays (maize) is a key crop that feeds millions of individuals around the world. The economic benefits of maize are challenged by the pathogen Aspergillus flavus, due to the production of the potent mycotoxin aflatoxin. Aflatoxin has been implicated in cancer in humans and in causing losses in animal production around the world, making food and feed contamination by aflatoxin a global issue. To address this problem, a systems biology approach was used to study the interaction between A. flavus and maize. This resulted in the detection of functional genes that are involved in the interaction between the two organisms. The study also led to the development of a mining tool that can be used to track genes implicated in the resistance of maize to A. flavus. This tool can be used by breeders and plant pathologists in future studies aiming at reducing losses caused by A. flavus and aflatoxin, which will benefit producers and consumers of maize and maize products.
Technical Abstract: A gene co-expression network was generated using a dual RNA-seq study with the fungal pathogen A. flavus and its plant host Z. mays during the initial 3 days of infection. The analysis deciphered novel pathways and mapped genes of interest in both organisms during the infection. This network revealed a high degree of connectivity in many of the previously recognized pathways in Z. mays such as jasmonic acid, ethylene, and reactive oxygen species (ROS). For the pathogen A. flavus, a link between aflatoxin production and vesicular transport was identified within the network. There was significant interspecies correlation of expression between Z. mays and A. flavus for a subset of 104 Z. mays, and 1942 A. flavus genes. This resulted in an interspecies subnetwork was enriched in multiple Z. mays genes involved in the production of reactive oxygen species. producing. In addition to the ROS from Z. mays, there was enrichment in the vesicular transport pathways and the aflatoxin pathway for A. flavus. Included in these genes, a key aflatoxin cluster regulator, AflS, was found to be co-regulated with multiple Z. mays ROS producing genes within the network, suggesting AflS may be monitoring host ROS levels. The entire gene expression network for both host and pathogen, and the subset of interspecies correlations, is presented as a tool for hypothesis generation and discovery for events in the early stages of fungal infection of Z. mays by A. flavus.