Morphological, genetic and epigenetic aspects of homoploid hybridization between Salvia officinalis L. and Salvia fruticosa Mill.

The inheritance of phenotypic, genetic and epigenetic traits in hybridization events is difficult to predict, as numerous evolutionary, ecological, and genetic factors can play a crucial role in the process of hybridization. In the middle Adriatic island of Vis, we investigated hybridization between Salvia officinalis and S. fruticosa at morphological, genetic and epigenetic levels. SSR results revealed that hybrid individuals were characterized by diploid set of chromosomes suggesting homoploid hybridization. A well-defined group that mostly comprised of F(1) generation individuals was detected. For the majority of analysed morphological characteristics, hybrids were placed in-between parental taxa, while at the same time, values of different genetic parameters were mostly higher in hybrids than in parental species. The results revealed a high contrast in the levels of phenotypic variability and epigenetic excitation between parental taxa. Environmental niche modelling confirmed that in the studied location S. officinalis experiences optimal climatological conditions, while S. fruticosa struggles with unsuitable conditions. Very low levels of gene flow between the parental species were detected. In addition, contrasting levels of epigenetic excitation in the studied groups clearly demonstrated the importance of an epigenetic response to an altered environment and confirmed the trans-generational nature of the epigenetic changes.