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ARS Home » Midwest Area » West Lafayette, Indiana » Crop Production and Pest Control Research » Research » Publications at this Location » Publication #282034

Title: Combating a global threat to a clonal crop: banana black sigatoka pathogen pseudocercospora fijiensis (synonym mycosphaerella fijiensis) genomes reveal clues for disease control

Author
item Arango Isaza, Rafael - University Of British Columbia
item Diaz Trujillo, Caucasella - Wageningen University And Research Center
item Dhillon, Braham - University Of British Columbia
item Aerts, Andrea - Joint Genome Institute
item Carlier, Jan - Centro De Cooperation Internationale En Recherche Agronomique Pour Le Development (CIRAD)
item Crane, Charles
item De Jong, Tristan - Wageningen University And Research Center
item De Vries, Ineke - Wageningen University And Research Center
item Goodwin, Stephen - Steve

Submitted to: PLoS Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/27/2016
Publication Date: 8/11/2016
Citation: Arango Isaza, R., Diaz Trujillo, C., Dhillon, B., Aerts, A., Carlier, J., Crane, C.F., De Jong, T., De Vries, I., Goodwin, S.B. 2016. Combating a global threat to a clonal crop: banana black sigatoka pathogen pseudocercospora fijiensis (synonym mycosphaerella fijiensis) genomes reveal clues for disease control. PLoS Genetics. 12(8):e1005876. doi:10.1371/journal.pgen.1005876.

Interpretive Summary: Black Sigatoka or leaf streak, caused by the fungus Mycosphaerella fijiensis, is one of the most devastating diseases of banana. Control of this disease requires weekly applications of fungicides in most cultivation areas with concomitant negative effects on humans and wildlife. Major problems for disease management are the rapid development of fungicide resistance within populations of the pathogen and the lack of effective genes for resistance in commonly grown clones of banana. To develop tools for molecular analysis and to identify genes involved in host-pathogen interactions, its genome was sequenced and compared to those of related plant-pathogenic fungi. The genome of M. fijiensis is greatly expanded mostly due to the presence of movable DNA elements. DNA-content analyses suggest that the genomes of two closely related members of the Sigatoka disease complex on banana, M. eumusae and M. musicola, also are expanded. Populations of M. fijiensis in Costa Rica had extraordinarily high levels of variation, but dramatic differences in the frequencies of fungicide resistance in sprayed versus an unsprayed field showed how rapidly resistance can develop. Infiltrations of purified protein from one predicted gene showed that it interacted with a resistance gene, the first proven incidence of this kind of interaction in banana. This information will be useful to evolutionary biologists and plant pathologists to better understand the genetics and evolution of host specificity and speciation mechanisms in fungi. Fungal geneticists can use the results to identify its pathogenicity factors and for understanding fungicide resistance and genome evolution. Banana breeders can use the purified protein to select for increased resistance in new banana cultivars.

Technical Abstract: Mycosphaerella fijiensis is the fungal pathogen that causes black Sigatoka or leaf streak disease of banana. Control of this disease requires weekly applications of fungicides in most cultivation areas. Major problems for disease management are fungicide resistance and the lack of effective genes for resistance in commonly grown clones of banana. To develop tools for molecular analysis and to identify genes involved in host-pathogen interactions, its genome was sequenced and mapped. Comparisons with related fungi revealed that the 74-Mb genome of M. fijiensis is greatly expanded mostly due to the presence of retrotransposons, making it the largest ascomycete genome sequenced to date. Melting-curve assays suggest that two closely related members of the Sigatoka disease complex on banana, M. eumusae and M. musicola, also have expanded genomes. Populations of M. fijiensis in Costa Rica had extraordinarily high levels of genetic variation including numerous chromosome-length polymorphisms. Dramatic differences in the frequencies of fungicide resistance in sprayed versus an unsprayed field showed that allele frequencies can change rapidly, presumably due to selection in sexually recombining populations. One of the gene models was MfAvr4, which is similar to a gene that encodes an effector in the tomato pathogen Cladosporium fulvum. Infiltration of purified MfAvr4 protein into the leaves of a resistant and susceptible banana cultivar resulted in a hypersensitive response in the former, indicating the presence of a homologue of the tomato Cf4 resistance gene in banana. Availability of the M. fijiensis genome sequence will facilitate the identification of its pathogenicity factors as well as understanding fungicide resistance and genome evolution.