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Abstract Detail


MSA - Systematics/Evolution

Talbot Brewer, Marin [1], Milgroom, Michael G. [1].

Phylogeography, diversity and genetics of the grapevine powdery mildew fungus Erysiphe necator.

Processes such as recombination, adaptation to new substrates or hosts, and introductions to new geographic ranges influence fungal evolution. Erysiphe necator provides a unique opportunity for studying fungal evolution, particularly speciation—a process that leads to the formation of new species— since distinct genetic lineages are present in its introduced range. Additionally, this fungus is a great model for the study of speciation since there is opportunity for host specialization and there is limited recombination, both of which may encourage species divergence. In order to understand the diversity and phylogenetic structure of populations in the introduced range of E. necator and their relationships with native populations from North America we used a multilocus sequencing approach. We sequenced four gene regions from 146 isolates obtained from both wild and cultivated Vitis spp. throughout native populations in eastern North America, and from cultivated V. vinifera from introduced populations in California, Oregon, France, Italy, and Australia. Multilocus sequence haplotypes from introduced populations formed two distinct genetic groups that likely represent separate introductions from eastern North America. As expected, the greatest diversity of haplotypes was found in native populations in eastern North America. However, we detected less recombination than would be expected in a fungus that regularly undergoes sexual reproduction. Additionally, we found a lineage specialized to V. rotundifolia, the muscadine grape present throughout the southeastern US, whereas we found no correlation between haplotypes and other Vitis species. Preliminary results on cloning of the mating type locus, which will be useful in genetic studies and in understanding population structure in this fungus, will be presented. Furthermore, studies aimed at characterizing progeny of sexual crosses to further understand the genetics and mating system of this fungus, as well as potential mechanisms of reproductive isolation among lineages, will be discussed.


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1 - Cornell University, Plant Pathology & Plant-Microbe Biology, 334 Plant Science Building, Ithaca, NY, 14853-5904, USA

Keywords:
powdery mildew
Grape
Erysiphe necator
Vitis
Plant pathogen
evolution
genetics
phylogeography
population biology.

Presentation Type: Oral Paper:Papers for Topics
Session: 29
Location: Cottonwood D/Snowbird Center
Date: Monday, July 27th, 2009
Time: 4:30 PM
Number: 29004
Abstract ID:842


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