Abstract Detail

Population Genetics

Brewer, Marin [1], Stewart, Jane [2], Glenn, Travis [3].

Extreme genetic diversity in populations of Exobasidium maculosum, an emerging blueberry pathogen.

Exobasidium leaf and fruit spot of blueberry (Vaccinium section Cyanococcus), caused by the fungus Exobasidium maculosum, is an emerging disease that has rapidly increased in prevalence throughout the southeastern USA since 2011. It has severely reduced fruit quality in many blueberry fields. Our objectives were to understand the genetic basis of disease emergence and if populations of E. maculosum differ based on geography, blueberry host species, or tissue type, i.e., leaf or fruit. We used multilocus sequencing of three loci and restriction site associated DNA markers (ddRAD) to estimate the genetic diversity of 88 isolates of E. maculosum from different blueberry host species in the southeastern USA and northeastern North America. Host species included V. corymbosum (highbush blueberry), V. corymbosum hybrids (southern highbush blueberry), V. virgatum (rabbiteye blueberry), and V. angustifolium (lowbush blueberry). Results showed that E. maculosum from the southeastern USA and northeastern North America are not different species, but are distinct populations due to either geographic isolation or host specialization. Population structure was detected within the southeastern USA based on geography, especially with ddRAD analyses, but no structure was identified based on original blueberry host species or tissue type. Although genetically structured, populations were extremely diverse. Each of the 88 isolates had a unique multilocus haplotype. Overall, these results suggest that the emergence of this disease is not due to a recent introduction, host jump, or the evolution of more aggressive genotypes of E. maculosum, but could be due to an increasing host population or an environmental change. Future work will examine the underlying basis of extreme genetic diversity in E. maculosum.

1 - University of Georgia, Plant Pathology, 2309 Miller Plant Science Building, Athens, GA, 30602, USA
2 - University of Georgia, Plant Pathology, 2105 Miller Plant Science Building, Athens, GA, 30602, USA
3 - University of Georgia, Environmental Health Science, 152 Environmental Health Science Building, Athens, GA, 30602, USA

Keywords:
none specified

Presentation Type: Oral Paper:Papers for Topics
Session: 71
Location: Salon 6/The Shaw Conference Centre
Date: Wednesday, July 29th, 2015
Time: 4:30 PM
Number: 71012
Abstract ID:424
Candidate for Awards:None