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United States Department of Agriculture

Agricultural Research Service

Research Project: Detection and Management of Pathogens in Strawberry and Vegetable Production Systems

Location: Crop Improvement and Protection Research

Title: Genetic analysis of Phytophthora nicotianae populations from different hosts using microsatellite markers

Author
item Biasi, Antonio
item Martin, Frank
item Cacciola, Santa
item Magnano Di San Lio, Gaetano
item Grunwald, Niklaus - Nik
item Schena, Leonardo

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2016
Publication Date: 4/25/2016
Citation: Biasi, A., Martin, F.N., Cacciola, S.O., Magnano Di San Lio, G., Grunwald, N.J., Schena, L. 2016. Genetic analysis of Phytophthora nicotianae populations from different hosts using microsatellite markers. Phytopathology. 106(9):1006-1014. doi: 10.1094/PHYTO-11-15-0299-R.

Interpretive Summary: This manuscript describes the use of simple sequence repeat molecular markers for investigating the population structure of Phytophthora nicotianae, a plant pathogen with a wide host range and distribution around the world. A total of 99 different genotypes were identified for 231 isolates collected from around the world. Isolates from citrus hosts were found to be genetically related regardless of their geographic origin, a higher level of variation was observed for isolates recovered from tobacco but isolates recovered from the same geographic area were similar.

Technical Abstract: Two hundred thirty-one isolates of P. nicotianae representing 14 populations from different host genera, including agricultural crops (Citrus, Nicotiana, and Lycopersicon), potted ornamental species in nurseries (Lavandula, Convolvulus, Myrtus, Correa and Ruta) and other plant genera of lesser economic importance, were characterized using SSR markers. A total of 99 multilocus genotypes (MLGs) were identified with a strong association between genetic grouping and host of recovery detected for all populations, with most MLGs associated to a single host genus. In a few cases MLGs were shared by different plant genera for isolates from ornamental hosts or genetically related genera. Significant differences in the structure of populations were revealed, although a prevalence of clonality was determined for all populations. Isolates from Citrus were found to be genetically related regardless of their geographic origin and were characterized by high genetic uniformity and inbreeding coefficients. Higher variability was observed in other populations and a significant geographical structuring was determined for isolates from Nicotiana. Detected differences were related to the propagation and cultivation systems of different cultures. Isolates obtained from Citrus species are more likely to be distributed worldwide with infected plant material while Nicotiana and Lycopersicon are propagated by seed, which would not contribute to the spread of the pathogen and result in a greater chance for geographic isolation of lineages. With regards to ornamental species in nurseries, the high genetic variation is likely to be the result of the introduction of diverse pathogen genotypes through the trade of infected plant material from various geographic origins, the presence of several hosts in the same nursery and genetic recombination through sexual reproduction of this heterothallic species.

Last Modified: 08/19/2017
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