Open AccessGlobal Hierarchical Gene Diversity Analysis Suggests the Fertile Crescent Is Not the Center of Origin of the Barley Scald Pathogen Rhynchosporium secalis
Author(s) -
Pascal L. Zaffarano,
Bruce A. McDonald,
Marcello Zala,
Celeste C. Linde
Publication year - 2006
Publication title -
phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.264
H-Index - 131
eISSN - 1943-7684
pISSN - 0031-949X
DOI - 10.1094/phyto-96-0941
Subject(s) - biology , hordeum vulgare , genetic diversity , mating type , genetic variation , genetics , restriction fragment length polymorphism , gene flow , genotype , geographical distance , allele , gene , botany , poaceae , population , demography , sociology
A total of 1,366 Rhynchosporium secalis isolates causing scald on barley, rye, and wild barley (Hordeum spontaneum) were assayed for restriction fragment length polymorphism loci, DNA fingerprints, and mating type, to characterize global genetic structure. The isolates originated from 31 field populations on five continents. Hierarchical analysis revealed that more than 70% of the total genetic variation within regions was distributed within a barley field. At the global level, only 58% of the total genetic variation was distributed within fields, while 11% was distributed among fields within regions, and 31% was distributed among regions. A significant correlation was found between genetic and geographic distance. These findings suggest that gene flow is common at the local level while it is low between regions on the same continent, and rare between continents. Analyses of multilocus associations, genotype diversity, and mating type frequencies indicate that sexual recombination is occurring in most of the populations. We found the highest allele richness in Scandinavia followed by Switzerland. This suggests that R. secalis may not have originated at the center of origin of barley, the Fertile Crescent, nor in a secondary center of diversity of barley, Ethiopia.