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United States Department of Agriculture

Agricultural Research Service

Research Project: Exotic and Emerging Plant Diseases of Horticultural Crops

Location: Horticultural Crops Research

Title: Evidence for multiple introductions and clonality in Spanish populations of Fusarium circinatum

Authors
item Berbegal, Monica -
item Perez-Sierra, A -
item Armengol, J -
item Grunwald, Niklaus

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 4, 2013
Publication Date: August 1, 2013
Citation: Berbegal, M., Perez-Sierra, A., Armengol, J., Grunwald, N.J. 2013. Evidence for multiple introductions and clonality in Spanish populations of Fusarium circinatum. Phytopathology. 103:851-861.

Interpretive Summary: Fusarium circinatum is a fungus causing an important plant disease affecting pine worldwide. The pathogen is thought to have been moved around the world with pine planting stock consisting most probably of infected seeds. We investigated the population structure of this pathogen in Spain and globally. A total of 223 isolates were studied from 5 regions in northern Spain and 8 countries. Variable molecular markers called microsatellites were used to determine genetic diversity within and among populations. This effort established that Spanish populations are structured into two distinct groups each one including one of the dominant clonal genotypes observed. This result suggests that two independent introductions occurred into the Spanish population. Possible introduction pathways from other countries and subsequent routes of dispersion of the plant pathogen F. circinatum in Spain are further discussed.

Technical Abstract: Fusarium circinatum is thought to have been moved around the world with pine planting stock consisting most probably of infected seeds. In this work we investigate the genetic structure of F. circinatum in Spain at a regional scale relative to global populations, and the relative contributions of reproduction mode to the pathogen demographic history in Spain. A total of 223 isolates were studied from 5 regions in northern Spain and 8 countries. Eight microsatellite markers revealed 66 multilocus genotypes (MLGs). Minimum spanning network analysis of MLGs by region within Spain as well as globally, discriminant analysis of principal components, and AMOVA revealed that Spanish populations are significantly differentiated and structured into two distinct groups, each one including one of the dominant genotypes observed. This result suggests that two independent introductions occurred into the Spanish population that subsequently underwent clonal divergence and admixture, and it is further supported by the clonality of F. circinatum in northern Spain based on several criteria tested. The maintenance of differentiation between the clusters could result from the low or non-existent contribution of sexual reproduction in Spanish F. circinatum populations. Possible introduction pathways from other countries and subsequent routes of dispersion of F. circinatum in Spain are further discussed.

Last Modified: 9/22/2014