|GUO, LEE - University Of Massachusetts|
|BREAKSPEAR, ANDREW - University Of Minnesota|
|ZHAO, GUOYI - University Of Massachusetts|
|XU, JINRONG - Purdue University|
|MA, LI-JUN - University Of Massachusetts|
Submitted to: Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2015
Publication Date: 2/1/2016
Citation: Guo, L., Breakspear, A., Zhao, G., Kistler, H.C., Xu, J., Ma, L. 2016. Conservation and divergence of the cyclic adenosine monophosphate-protein kinase A (cAMP–PKA) pathway in two plant-pathogenic fungi: Fusarium graminearum and F. verticillioides. Molecular Plant Pathology. 17(2):196-209. doi: 10.1111/mpp.12272.
Interpretive Summary: Fusarium graminearum (Fg), a major pathogen of cultivated cereals, is responsible for billions of dollars in agricultural losses. There is a growing interest in understanding the mechanisms by which genes in this harmful pathogen are turned on and off, especially if this regulation controls the ability of the fungi to cause disease or to allow toxins to contaminate food. Advanced methods for studying gene expression in Fg and a related Fusarium species provided a unique opportunity to understand the regulation of genes associated with disease and toxin production. Applying a comparative approach, we developed a computational process to systematically discover evolutionarily conserved portions of the genes that control when and where they are expressed. Factors which regulate gene expression of important traits potentially could be exploited for disease control measures. These disease management strategies may involve disruption of vital fungal developmental pathways. The primary users of the research in this publication will be other scientists engaged in research to improve disease management on small grain crops.
Technical Abstract: The cyclic AMP (cAMP)-PKA pathway is a central signaling cascade that transmits extracellular stimuli and governs cell responses through the second messenger cAMP. The importance of cAMP signaling in fungal biology has been well documented. Two key conserved components, adenylate cyclase (AC) and catalytic subunit of PKA (CPKA), have been functionally characterized. However, other genes involved in this signaling pathway and their regulation are not well understood in filamentous fungi. Here, we performed comparative transcriptomics of AC and CPKA mutants in two closely-related fungi: Fusarium graminearum (Fg) and F. verticillioides (Fv). Combining available Fg transcriptomics and phenomics data, we reconstructed the Fg cAMP signaling pathway. A computational program that combines sequence conservation and patterns of orthologous gene expression was developed to facilitate global transcriptomic comparison between different organisms. We observed highly correlated expression patterns for most orthologs (80%) between Fg and Fv and identified a subset of 482 (6%) diverged orthologs, whose expression in one genome is at least 50% higher than that in the other genome, under all conditions. This enables the dissection of the conserved and unique portions of the cAMP-PKA pathway. Whereas the conserved portions control essential functions such as metabolism, cell cycle, chromatin remodeling, and oxidative stress response, diverged portions play more species-specific roles such as production and detoxification of secondary metabolites unique to each species. The divergence of this central signaling pathway suggests its direct contribution in fungal speciation.