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United States Department of Agriculture

Agricultural Research Service

Research Project: MOLECULAR AND GENETIC MECHANISMS OF FUNGAL DISEASE RESISTANCE IN GRAIN CROPS

Location: Crop Production and Pest Control Research

Title: Finished genome of the fungal wheat pathogen Mycosphaerella graminicola reveals dispensome structure, chromosome plasticity and stealth pathogenesis

Authors
item Goodwin, Stephen
item M'Barek, Sarrah Ben -
item Dhillon, Braham -
item Wittenberg, Alexander H. -
item Crane, Charles
item Van Der Lee, Theo A. -
item Grimwood, Jane -
item Aerts, Andrea -
item Antoniw, John -
item Bailey, Andy -
item Bluhm, Burt -
item Bowler, Judith -
item Bristow, Jim -
item Canto-Canche, Blondy -
item Churchill, Alice -
item Conde-Ferraez, Laura -
item Cools, Hans -
item Coutinho, Pedro -
item Csukai, Michael -
item Dehal, Paramvir -
item DE Wit, Pierre -
item Donzelli, Bruno
item Foster, Andres -
item Hammond-Kosack, Kim -
item Hane, James -
item Henrissat, Bernard -
item Killian, Andrzej -
item Koopmann, Edda -
item Kourmpetis, Yiannis -
item Kuzniar, Arnold -
item Lindquist, Erika -
item Lombard, Vincent -
item Maliepaard, Chris -
item Martins, Natalia -
item Mahrabi, Rahim -
item Oliver, Richard -
item Ponomarenko, Alisa -
item Rudd, Jason -
item Salamov, Asaf -
item Schmutz, Jeremy -
item Schouten, Henk -
item Shapiro, Harris -
item Stergiopoulos, Ioannis -
item Torriani, Stefano F. -
item Tu, Hank -
item DE Vries, Ronald -
item Wiebenga, Ad -
item Zwiers, Lute-Harm -
item Grigoriev, Igor -
item Kema, Gert H. -

Submitted to: PLoS Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 28, 2011
Publication Date: June 9, 2011
Citation: Goodwin, S.B., M'Barek, S., Dhillon, B., Wittenberg, A.J., Crane, C.F., Van Der Lee, T.J., Grimwood, J., Aerts, A., Antoniw, J., Bailey, A., Bluhm, B., Bowler, J., Bristow, J., Canto-Canche, B., Churchill, A., Conde-Ferraez, L., Cools, H., Coutinho, P.M., Csukai, M., Dehal, P., De Wit, P., Donzelli, B., Foster, A.J., Hammond-Kosack, K., Hane, J., Henrissat, B., Killian, A., Koopmann, E., Kourmpetis, Y., Kuzniar, A., Lindquist, E., Lombard, V., Maliepaard, C., Martins, N., Mahrabi, R., Oliver, R., Ponomarenko, A., Rudd, J., Salamov, A., Schmutz, J., Schouten, H.J., Shapiro, H., Stergiopoulos, I., Torriani, S.F., Tu, H., De Vries, R.P., Wiebenga, A., Zwiers, L., Grigoriev, I.V., Kema, G.J. 2011. Finished genome of the fungal wheat pathogen Mycosphaerella graminicola reveals dispensome structure, chromosome plasticity and stealth pathogenesis. PLoS Genetics. Available at: http://www.plosgenetics.org/article/info%3Adoi%2F10.1371%2Fjournal.pgen.1002070.

Interpretive Summary: The plant-pathogenic fungus Mycosphaerella graminicola (asexual stage: Septoria tritici) causes Septoria tritici blotch of wheat. This disease can cause economically important damage of wheat crops and is a potential threat to global food production. Control of the disease has been hampered by a limited understanding of the genetic and biochemical bases of pathogenicity, including mechanisms of infection and of resistance in the host. Unlike most other plant pathogens, M. graminicola has a long latent period during which it seems able to evade host defenses, but the genetic basis for this trait is not known. To address this problem, the genome of the fungus was sequenced to completion through the Community Sequencing Program of the U.S. Department of Energy’s Joint Genome Institute. The finished genome sequence contains 21 chromosomes, eight of which could be lost with no visible effect on the fungus so are dispensable. The dispensable chromosomes were different from those in the core genome and appear to have originated by ancient horizontal gene transfer from an unknown donor species. A surprising feature of the M. graminicola genome was a low number of genes for enzymes that break down plant cell walls; many of these genes may have been lost during evolution to evade detection by plant defense mechanisms leading to the current stealth pathogenicity. This information will be useful to fungal geneticists and evolutionary biologists to better understand the genetics and evolution of dispensable chromosomes and stealth pathogenicity in M. graminicola. Fungal biologists can use the sequence to knock out gene expression for functional genomics analyses of interacting genetic networks. Plant pathologists may be able to use this information to design better strategies for disease management, particularly once the biochemical bases for the genetic interactions between host and pathogen are better understood.

Technical Abstract: A finished genome was obtained for Mycosphaerella graminicola, the fungal cause of septoria tritici blotch and a global threat to wheat production, containing thirteen core and eight dispensable chromosomes. The latter, called collectively the dispensome, were dynamic in field and progeny isolates. They were distinct in structure, gene and repeat content but contained parts from each core chromosome, suggesting ancient horizontal gene transfer followed by elevated recombination as the major forces driving their evolution. The genome of M. graminicola had far fewer genes for cell wall-degrading enzymes and secondary metabolites compared to other plant pathogens. The stealth pathogenesis of M. graminicola probably involves degradation of proteins rather than carbohydrates to evade host defenses during the biotrophic stage of infection and may have evolved from an endophytic ancestor.

Last Modified: 7/31/2014
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