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ARS Home » Midwest Area » Lexington, Kentucky » Forage-animal Production Research » Research » Publications at this Location » Publication #296498
Title: Currencies of mutualisms: Sources of alkaloid genes in vertically transmitted epichloae

Author
item SCHARDL, CHRISTOPHER - University Of Kentucky
item YOUNG, CAROLYN - Samuel Roberts Noble Foundation, Inc
item PAN, JUAN - University Of Kentucky
item FLOREA, SIMONA - University Of Kentucky
item TAKACH, JOHANNA - Samuel Roberts Noble Foundation, Inc
item PANACCIONE, DANIEL - West Virginia University
item FARMAN, MARK - University Of Kentucky
item WEBB, JENNIFER - University Of Kentucky
item JAROMCZYK, JOLANTA - University Of Kentucky
item CHARLTON, NIKKI - Samuel Roberts Noble Foundation, Inc
item HAGABHYRU, PADMAJA - University Of Kentucky
item CHEN, LI - University Of Kentucky
item SHI, CHONG - University Of Kentucky
item LEUCHTMANN, ADRIAN - Eth Zurich

Submitted to: Toxins
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/29/2013
Publication Date: 6/6/2013
Citation: Schardl, C.L., Young, C.A., Pan, J., Florea, S., Takach, J.E., Panaccione, D.G., Farman, M.L., Webb, J.S., Jaromczyk, J., Charlton, N.D., Hagabhyru, P., Chen, L., Shi, C., Leuchtmann, A. 2013. Currencies of mutualisms: Sources of alkaloid genes in vertically transmitted epichloae. Toxins. 5:1064-1088.

Interpretive Summary: The epichloae (Epichloë and Neotyphodium species), a monophyletic group of fungi in the family Clavicipitaceae, are systemic symbionts of cool-season grasses (Poaceae subfamily Poöideae). Most epichloae are vertically transmitted in seeds (endophytes), and most produce alkaloids that attack nervous systems of potential herbivores. These protective metabolites include ergot alkaloids and indole-diterpenes (tremorgens), which are active in vertebrate systems, and lolines and peramine, which are more specific against invertebrates. Several Epichloë species have been described which are sexual and capable of horizontal transmission, and most are vertically transmissible also. Asexual epichloae are mainly or exclusively vertically transmitted, and many are interspecific hybrids with genomic contributions from two or three ancestral Epichloë species. Here we employ genome-scale analyses to investigate the origins of biosynthesis gene clusters for ergot alkaloids (EAS), indole-diterpenes (IDT), and lolines (LOL) in 12 hybrid species. In each hybrid, the alkaloid-gene and housekeeping-gene relationships were congruent. Interestingly, hybrids frequently had alkaloid clusters that were rare in their sexual ancestors. Also, in those hybrids that had multiple EAS, IDT or LOL clusters, one cluster lacked some genes, usually for late pathway steps. Possible implications of these findings for the alkaloid profiles and endophyte ecology are discussed.

Technical Abstract: The epichloae (Epichloë and Neotyphodium species), a monophyletic group of fungi in the family Clavicipitaceae, are systemic symbionts of cool-season grasses (Poaceae subfamily Poöideae). Most epichloae are vertically transmitted in seeds (endophytes), and most produce alkaloids that attack nervous systems of potential herbivores. These protective metabolites include ergot alkaloids and indole-diterpenes (tremorgens), which are active in vertebrate systems, and lolines and peramine, which are more specific against invertebrates. Several Epichloë species have been described which are sexual and capable of horizontal transmission, and most are vertically transmissible also. Asexual epichloae are mainly or exclusively vertically transmitted, and many are interspecific hybrids with genomic contributions from two or three ancestral Epichloë species. Here we employ genome-scale analyses to investigate the origins of biosynthesis gene clusters for ergot alkaloids (EAS), indole-diterpenes (IDT), and lolines (LOL) in 12 hybrid species. In each hybrid, the alkaloid-gene and housekeeping-gene relationships were congruent. Interestingly, hybrids frequently had alkaloid clusters that were rare in their sexual ancestors. Also, in those hybrids that had multiple EAS, IDT or LOL clusters, one cluster lacked some genes, usually for late pathway steps. Possible implications of these findings for the alkaloid profiles and endophyte ecology are discussed.