Patterns of genetic diversity and differentiation in resistance gene clusters of two hybridizing European Populus species

Casey, Céline; Stölting, Kai N.; Barbará, Thelma; González-Martínez, Santiago C.; Lexer, Christian

doi:10.1007/s11295-015-0904-8

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Patterns of genetic diversity and differentiation in resistance gene clusters of two hybridizing European Populus species

Casey, Céline Unit of Ecology and Evolution, Department of Biology, University of Fribourg, Switzerland - Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, Canada
Stölting, Kai N. Unit of Ecology and Evolution, Department of Biology, University of Fribourg, Switzerland
Barbará, Thelma Unit of Ecology and Evolution, Department of Biology, University of Fribourg, Switzerland
González-Martínez, Santiago C. Department of Forest Ecology and Genetics, INIA-Forest Research Centre, Madrid, Spain
Lexer, Christian Unit of Ecology and Evolution, Department of Biology, University of Fribourg, Switzerland - Department of Botany and Biodiversity Research, University of Vienna, Austria

24.07.2015

Published in:

Tree Genetics & Genomes. - 2015, vol. 11, no. 4, p. 1–12

English Resistance genes (R-genes) are essential for long-lived organisms such as forest trees, which are exposed to diverse herbivores and pathogens. In short-lived model species, R-genes have been shown to be involved in species isolation. Here, we studied more than 400 trees from two natural hybrid zones of the European Populus species Populus alba and Populus tremula for microsatellite markers located in three R-gene clusters, including one cluster situated in the incipient sex chromosome region. The results indicate that all three R-gene clusters present extensive linkage disequilibrium (LD). Outlier tests suggest balancing selection as a potential driver of R-gene diversity, but divergent selection was also detected. Nucleotide-binding site leucine-rich repeat (NBS-LRR) type R-gene clusters exhibit low species differentiation and appear to be affected by shared selection pressures between species, recurrent interspecific gene flow, or both. Our results are consistent with a role for R-gene clusters in the evolution of chromosome XIX, recently put forward as an incipient sex chromosome in Populus.

Faculty

Faculté des sciences et de médecine

Department

Département de Biologie

Language