Terpene Synthase Genes in Quercus robur – Gene Characterization, Expression and Resulting Terpenes Due to Cockchafer Feeding

Abstract

Root herbivory caused by larvae of the forest cockchafer (Melolontha hippocastani) enhances the impact of drought on trees, particularly in oak forest rejuvenations. In Germany, geographically distant oak stands show differences in infestation strength by the forest cockchafer. While in Southwestern Germany this insect causes severe damage, oak forests in northern Germany are rarely infested. It is known that root-released volatile organic compounds (VOCs) are perceived by soil herbivores, thus guiding the larvae toward the host roots. In this work, we exposed seedlings of two distant oak provenances to forest cockchafer larvae and studied their population genetic properties, their root-based VOC chemotypes, their attraction for larvae and terpene synthase gene expression. Based on nuclear and chloroplast marker analysis, we found both oak populations to be genetically highly variable while showing typical patterns of migration from different refugial regions. However, no clear association between genetic constitution of the different provenances and the abundance of cockchafer populations on site was observed. In contrast to observations in the field, bioassays revealed a preference of the larvae for the northeastern oak provenance. The behavior of larvae was most likely related to root-released volatile terpenes and benzenoids since their composition and quantity differed between oak populations. We assume repellent effects of these compounds because the populations attractive to insects showed low abundance of these compounds. Five different oak terpene synthase (TPS) genes were identified at the genomic level which can be responsible for biosynthesis of the released terpenes. TPS gene expression patterns in response to larval feeding revealed geographic variation rather than genotypic variation. Our results support the assumption that root-released VOC are influencing the perception of roots by herbivores.

In Vitro Production and Exudation of 20-Hydroxymaytenin from Gymnosporia heterophylla (Eckl. and Zeyh.) Loes. Cell Culture

“…We also report the partial sequences of the hypothetical FRS gene and its gene expression from G. heterophylla for the first time. We could only amplify an 800 bp fragment, but this fragment was long enough to identify as the hypothetical FRS gene based on the Blastn and phylogenic analyses [ 51 , 52 ]. Since the current information of the FRS gene is very limited (only nine FRS genes from four plant species were reported), we believe that our report can provide more diversity in FRS sequences.…”

The role of oak wood in the mint and floral notes of whisky: identification of common terpenoids by aromatic fractionation

“…Terpene synthases, key enzymes in terpenoids biosynthesis, then catalyse rearrangements and cyclisation producing a wide variety of monoterpene end-products (Black et al, 2015). Oak Quercus species are one of the strongest emitters of monoterpenoids (Loreto et al, 2002), and several terpene synthase genes coding for these enzymes have been identified (Creyaufmüller et al, 2018;Loreto et al, 2009). Despite this they do not contribute to aroma directly.…”