rmtA-dependent transcriptome and its role in secondary metabolism, environmental stress, and virulence in Aspergillus flavus

Authors: SATTERLEE, TIMOTHY - Northern Illinois University; ENTWISTLE, SARAH - Northern Illinois University; YIN, YANBIN - Northern Illinois University; Cary, Jeffrey; Lebar, Matthew; LOSADA, LILIANA - J Craig Venter Institute; CALVO, ANA - Northern Illinois University

Submitted to: G3, Genes/Genomes/Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/1/2019
Publication Date: 12/1/2019
Citation: Satterlee, T., Entwistle, S., Yin, Y., Cary, J.W., Lebar, M.D., Losada, L., Calvo, A.M. 2019. rmtA-dependent transcriptome and its role in secondary metabolism, environmental stress, and virulence in Aspergillus flavus. G3, Genes/Genomes/Genetics. 9(12):4087-4096. https://doi.org/10.1534/g3.119.400777.
DOI: https://doi.org/10.1534/g3.119.400777

Interpretive Summary: This work describes experiments that have been conducted in an effort to better understand the genetic mechanisms that control aflatoxin production, response to stress and virulence in Aspergillus flavus. Aflatoxins are toxic and carcinogenic compounds often produced by the fungi, Aspergillus flavus during growth on crops such as corn, peanuts, cottonseed, and treenuts. Because of the potential health risks, aflatoxin contamination of food and feed crops is also of great economic importance to farmers who cannot sell their crops due to strict domestic and international regulatory guidelines with regards to aflatoxin contamination. A previous study identified a gene, designated rmtA, from A. flavus that when inactivated significantly impacted development of the fungus and greatly reduced production of aflatoxins. Therefore rmtA appeared to be acting as a global regulator of A. flavus growth and secondary metabolim. We performed additional experiments to determine the extent to which rmtA influenced the expression of all genes in A. flavus. We found that rmtA affected the expression of over 2000 genes some of which are involved in production of numerous secondary metabolites, response to environmental stress, and the ability of the fungus to infect plants. Identification of rmtA will add to our knowledge of regulation of growth and toxin production in A. flavus and this in turn will help in devising strategies for eliminating fungal toxin contamination of food and feed crops.

Technical Abstract: Aspergillus flavus colonizes numerous oil seed crops such as maize, peanuts, treenuts and cottonseed worldwide, contaminating them with aflatoxins and other harmful toxins. Previously our lab characterized the gene rmtA, which encodes an arginine methyltransferase in A. flavus, and demonstrated its role governing the expression of regulators in the aflatoxin gene cluster and subsequent synthesis of toxin. Furthermore, our studies revealed that rmtA also controls conidial and sclerotial development implicating it as an epigenetic regulator in A. flavus. To confirm this, we performed a RNA sequencing analysis to ascertain the extent of rmtA’s influence on the transcriptome of A. flavus. In this analysis we identified over 2000 genes that were rmtA-dependent. Of those genes, we identified those that were involved in production of secondary metabolites, response to environmental stress, and genes active during plant virulence.