Cross-transferability-based identification and validation of simple sequence repeat (SSR) markers in oaks of western Himalayas

Cross-amplification is a cost-effective method to extend the applicability of SSR markers to closely related taxa which lack their own sequence information. In the present study, 35 SSR markers developed in four oak species of Europe, North America and Asia were selected and screened in five species of the western Himalayas. Fifteen markers were successfully amplified in Quercus semecarpifolia, followed by 11 each in Q. floribunda and Q. leucotrichophora, 10 in Q. glauca, and 9 in Q. lanata. Except two primer pairs in Q. semecarpifolia, all were found to be polymorphic. Most of the positively cross-amplified SSRs were derived from the Asian oak, Q. mongol ica. The genotyping of 10 individuals of each species with positively cros-samplified SSRs displayed varied levels of polymorphism in the five target oak species, viz., QmC00419 was most polymorphic in Q. floribunda, QmC00716 in Q. glauca and Q. lanata, QmC01368 in Q. leucotrichophora, and QmCO2269 in Q. semecarpifolia. Among five oak species, the highest gene diversity was depicted in Q. lanata and Q. semecarpifolia with expected heterozygosity (He = 0.72), while the minimum was recorded for Q. leucotrichophora and Q. glauca (He = 0.65). The SSRs validated here provide a valuable resource to carry out further population genetic analysis in oaks of the western Himalayas.