Development and characterization of microsatellite markers for the rubber tree powdery mildew pathogen Oidium heveae

Powdery mildew, caused by Oidium heveae, is a major threat to rubber plantations worldwide. Population studies are scarce for this pathogen due to the lack of polymorphic molecular markers. In this study, sixteen polymorphic microsatellite loci were identified using DNA extracted from single lesions based on the whole-genome sequences of the pathogen. Primers of these loci were applied to 138 O. heveae samples from five counties in Hainan, China. The number of alleles per locus ranged from 2 to 11 and the gene diversity varied from 0.014 to 0.728. In total, 119 multilocus genotypes (MLGs) were observed for the 138 samples. However, only one sample was significantly distinct from the other samples base on DAPC analysis. Further study indicated that there were three subclusters for the other 137 samples, but no evidence for regional genotypic subdivision was identified. The microsatellite markers developed are very useful to study the genetic structure and the dispersal route of O. heveae, especially as it can use DNA extracted directly from infected leaves.