Alle interesserede er velkomne til foredraget, som afholdes den 22. april kl. 15 i auditorium 02, August Krogh Institutet på Københavns Universitet.

Abstract:

'From the Andes to Ireland, Tracking the worldwide migrations and evolutionary history of the potato late blight pathogen'

Dr Jean Ristaino, North Carolina State University

Potato late blight, caused by the oomycete pathogen Phytophthora infestans is considered the most important biotic constraint to potato production worldwide and is a major threat to food security. New strains of the pathogen have migrated from South America on multiple occasions to cause significant losses for US growers. In 2009, potato and tomato late blight epidemics were the worst in modern history in the US due to a "perfect storm" of widespread inoculum distribution and conducive weather. We have previously examined the global migrations and evolutionary history of P. infestans in modern potato crops and identified the source and strain that caused the 19th century Irish potato famine from archival materials. We used mitochondrial DNA sequences and identified the Ia mtDNA haplotype of P. infestans in 19th century epidemics from Europe, the US and Ireland. Multilocus sequence data from nuclear and mitochondrial loci support an Andean origin of P. infestans and also suggest that the source of inoculum for the potato famine epidemics in Ireland were from the Andean region. We are currently tracking the waves of migration of the pathogen that occurred in the late 19th and early 20th century into the US using historic samples and have identified the mid-century migration of the Ib mtDNA haplotype and host shifts of the pathogen to wild Solanum species on two continents. The evolutionary history of the entire Ic clade of Phytophthora (P. infestans, P. andina, P. mirabilis, P. ipomoeae and P. phaseoli ) is under investigation using whole mt genome sequences.

· Guo, L., Zhu, X., Hu, C. and Ristaino, J. B. 2010. Genetic structure of Phytophthora infestans populations in China indicates multiple migration events. Phytopathology: accepted.

· Olivia, R. F., Flier, W., Kroon, L., Ristaino, J. B. and Forbes, G. A. 2010. Phytophthora andina, a newly identified heterothallic pathogen of Solanaceous hosts in the Andean highlands. Plant Pathology: in press.

· Haas, B. J., et al. 2009. Genome sequence and comparative analysis of the Irish potato famine pathogen Phytophthora infestans. Nature: 461:393-398.

· Ristaino, J. B and C. Hu. 2009. DNA sequence analysis of the Late-Blight Pathogen gives clues to the world-wide migration. Acta Horticulturae: 834:27-40.

· Cafe-Filho, A. C. and Ristaino J. B. 2008. Fitness of isolates of Phytophthora capsici insensitive to mefenoxam from squash and pepper fields in North Carolina. Plant Dis. 92: 1439-1443.

· Gomez, L. Hu, C., Olivia, R., Forbes, G. and Ristaino, J. B. 2008. Phylogenetic relationships of a new species, Phytophthora andina, from the highlands of Ecuador that is closely related to the Irish Potato famine pathogen Phytophthora infestans. Mycologia 100:590-602.

· Ristaino, J. B., Johnson, M., Blanco-Meneses, M., Lui, B. and 2007. Identification of the Tobacco blue mold pathogen, Peronospora tabacina by PCR. Plant Dis. 91:685-691.

· Gomez, L., Carbone, I., and Ristaino, J. B. 2007. An Andean origin for Phytophthora infestans inferred from nuclear and mitochondrial DNA sequences. Proc. Nat. Acad. Sci. 104:3306-3311.

· Avila-Adame, C., Gómez-Alpizar, L., Buell, R. C. and Ristaino, J. B. 2006. Mitochondrial genome sequencing of the haplotypes of the Irish Potato famine pathogen, Phytophthora infestans. Curr. Gen. 49:39-46.

· May, K. J. and Ristaino, J. B. 2004. Identify of the Mitochondrial DNA Haplotype(s) of Phytophthora infestans in Historical Specimens from the Irish Potato Famine. Mycol. Res. 108:171-179.

· Ristaino, J. B., Groves, C. T., and Parra, G. 2001. PCR Amplification of the Irish Potato Famine Pathogen from Historic Specimens. Nature 41:695-697