High Genetic Differentiation among European White Oak Species (Quercus spp.) at a Dehydrin Gene

Dehydryn genes are involved in plant response to environmental stress and may be useful to examine functional diversity in relation to adaptive variation. Recently, a dehydrin gene (DHN3) was isolated in Quercus petraea and showed little differentiation between populations of the same species in an attitudinal transect In the present study, inter- and intraspedfic differentiation patterns in closely related and interfertile oaks were investigated for the first time at the DHN3 locus. A four-oak-species stand (Quercus frainetto Ten., Q. petraea (Matt.) Liebl., Q. pubescens Willd. Q. robur L.) and two populations for each of five white oak species (Q. frainetto Ten., Q. petraea (Matt.) Liebl., Q. pubescens Q. robur L. and Q. pedunculiflora K. Koch) were analyzed. Three alleles shared by all five oak species were observed. However, only two alleles were present in each population, but with different frequencies according to the species. At population level, all interspecific pairs of populations showed significant differentiation, except for pure Q. robur and Q. pedunculiflora populations. In contrast, no significant differentiation (p > 0.05) was found among conspecific populations. The DHN3 locus proved to be vet), useful to differentiate Q. frainetto and Q. pubesens from Q. pedunculiflora (F-ST = 0.914 and 0.660, respectively) and Q. robur (F-ST = 0.858 and 0.633, respectively). As expected, the lowest level of differentiation was detected between the most closely related species,Qrobur and Q. pedunculiflora(F-ST = 0.020). Our results suggest that DHN3 can be an important generic marker for differentiating among European white oak species.