Inheritance of specific secondary volatile metabolites in buds of white birch Betula pendula and Betula pubescens hybrids

Despite the differences in ploidy and in the timing of flowering, two species of white birch, Betula pendula and Betula pubescens often form viable hybrids in places of their joint growth. Recognition of such hybrids by their morphological features is very difficult or impossible. On the other hand, it could be assumed that substantial differences can be found in the secondary metabolites whose composition is determined mainly by genetic factors. However, the inheritability of biosynthesis of secondary birch metabolites is unknown. We investigated the bud volatile organic compounds (VOCs) of the artificial hybrids of these birches and compared them with specific metabolites of pure parent species. The bud VOCs were determined by a combination of head-space microextraction with gas chromatography-mass spectrometry. As the result, we found that: (a) hybrids clearly show dominant inheritance along the maternal line and (b) the buds of hybrid plants have characteristic features of VOCs composition, which allows for definitive conclusions about hybrid origins in some cases.