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United States Department of Agriculture

Agricultural Research Service

Research Project: EXOTIC, EMERGING, RE-EMERGING, AND INVASIVE PLANT DISEASES OF HORTICULTURAL CROPS

Location: Horticultural Crops Research

Title: Genetic diversity of Phytophthora infestans in the Northern-Andean region

Authors
item Cardenas, M -
item Grajales, A -
item Sierra, R -
item Rojas, A -
item Garavito, M -
item Lozano, G -
item Gonzalez-Almario, A -
item Vargas, A -
item Marin, M -
item Fermin, G -
item Lagos, L -
item Grunwald, Niklaus
item Bernal, A -
item Salazar, C -
item Restrepo, S -

Submitted to: BMC Evolutionary Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 9, 2011
Publication Date: February 9, 2011
Citation: Cardenas, M., Grajales, A., Sierra, R., Rojas, A., Garavito, M., Lozano, G., Gonzalez-Almario, A., Vargas, A., Marin, M., Fermin, G., Lagos, L.E., Grunwald, N.J., Bernal, A., Salazar, C., Restrepo, S. 2011. Genetic diversity of Phytophthora infestans in the Northern-Andean region. BMC Evolutionary Biology. 12:23.

Interpretive Summary: Phytophthora infestans (Mont.) de Bary, the causal agent of potato late blight, is responsible for tremendous crop and economic losses worldwide. Countries in the northern part of the Andes dedicate a large proportion of the highlands to the production of potato and, more recently, solanaceous fruits such as cape gooseberry (Physalis peruviana) and tree tomato (Solanum betaceum), all of which are hosts of this oomycete. In the Andean region, P. infestans populations have been well characterized in Ecuador and Peru, but are poorly studied in Colombia and Venezuela. To understand the relationships among the P. infestans populations in the Northern part of the Andes, four nuclear and one mitochondrial DNA regions were analyzed in 92 isolates of P. infestans sampled from different hosts in Colombia, Ecuador, and Venezuela. Low genetic diversity was found in the Andean region where potato has its center of origin, revealing the presence of clonal populations of the pathogen in this region. The P. infestans population genetic analysis suggests that the North Andean region is inhabited by a genetically moderately diverse population with subdivision between the Southwestern and Eastern Andes as a result of potato seed self sufficiency given that the pathogen can move with seed potatoes.

Technical Abstract: Phytophthora infestans (Mont.) de Bary, the causal agent of potato late blight, is responsible for tremendous crop and economic losses worldwide. Countries in the northern part of the Andes dedicate a large proportion of the highlands to the production of potato and, more recently, solanaceous fruits such as cape gooseberry (Physalis peruviana) and tree tomato (Solanum betaceum), all of which are hosts of this oomycete. In the Andean region, P. infestans populations have been well characterized in Ecuador and Peru, but are poorly studied in Colombia and Venezuela. To understand the relationships among the P. infestans populations in the Northern part of the Andes, four nuclear (ITS, Ras, ß-tubulin and Avr3a) and one mitochondrial (Cox1) regions were analyzed in 92 isolates of P. infestans sampled from different hosts in Colombia, Ecuador, and Venezuela. Low genetic diversity was found in the Andean region where potato has its center of origin, revealing the presence of clonal populations of the pathogen in this region. Nonetheless, sexual reproduction generates low frequency heterozygotes as consequence of a high migration rate among populations but with a poor effective gene flow. Consistently genetic differentiation exists among isolates from different regions, a pattern that might be explained by seed trading dynamics. The P. infestans population genetic analysis presented suggests that the North Andean region is inhabited by a polymorphic population with subdivision between the Southwestern and Eastern Andes as a result of potato seed self sufficiency. Additionally, Venezuela reflects a partial historic isolation that is being reinforced by a recent self-sufficiency. In summary, the P. infestans demography is mainly shaped by genetic drift and migration although diversifying selection drive the generation of new haplotypes in adaptive genes as in the Avr3a effector gene.

Last Modified: 9/21/2014
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