Spatial Patterns of Brown Rot Epidemics and Development of Microsatellite Markers for Analyzing Fine-Scale Genetic Structure of Monilinia fructicola Populations Within Peach Tree Canopies

Authors

Sydney E. Everhart, University of Nebraska-LincolnFollow
A. Askew, University of Georgia, Athens
L. Seymour, University of Georgia, Athens
T. C. Glenn, University of Georgia, Athens
H. Scherm, University of Georgia, AthensFollow

Date of this Version

2012

Citation

Plant Health Progress doi:10.1094/PHP-2012-0723-04-RS

Comments

Copyright © 2012 Plant Management Network

Abstract

To better understand the fine-scale spatial dynamics of brown rot disease and corresponding fungal genotypes, we analyzed three-dimensional spatial patterns of pre-harvest fruit rot caused by Monilinia fructicola in individual peach tree canopies and developed microsatellite markers for canopy-level population genetics analyses. Using a magnetic digitizer, high-resolution maps of fruit rot development in five representative trees were generated, and M. fructicola was isolated from each affected fruit. To characterize disease aggregation, nearest-neighbor distances among symptomatic fruit were calculated and compared with appropriate random simulations. Within-canopy disease aggregation correlated negatively with the number of diseased fruit per tree (r = −0.827, P = 0.0009), i.e., aggregation was greatest when the number of diseased fruit was lowest. Sixteen microsatellite primers consistently amplified polymorphic regions in a geographically diverse test population of 47 M. fructicola isolates. None of the test isolates produced identical multilocus genotypes, and the number of alleles per locus ranged from 2 to 16. We are applying these markers to determine fine-scale population structure of the pathogen within and among canopies.