Genotype- and provenance-related variation in the leaf surface secondary metabolites of silver birch
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CitationDeepak, Maya. Lihavainen, Jenna. Keski-Saari, Sarita. Kontunen-Soppela, Sari. Salojärvi, Jarkko. Tenkanen, Antti. Heimonen, Kaisa. Oksanen, Elina. Keinänen, Markku. (2018). Genotype- and provenance-related variation in the leaf surface secondary metabolites of silver birch. CANADIAN JOURNAL OF FOREST RESEARCH, 48 (5) , 494-505. 10.1139/cjfr-2017-0456.
The cuticular wax layer on silver birch (Betula pendula Roth) leaves is rich in cyclic secondary metabolites that provide defense against various environmental factors. Micropropagated trees from the southern (60°N), central (62°N), and northern (66°N) latitudes of Finland were grown in a common garden setup and quantified for variation in leaf surface secondary metabolites and other leaf traits, and their association with genotype and provenance was studied. The 12 genotypes studied differed greatly in the quantity of surface secondary metabolites, both for individual flavonoid and triterpenoid aglycones and for the overall metabolite profile. Qualitative differences were observed for one triterpenoid that was present in a single genotype (R3). The variance explained by the provenance was low (between 1% and 36%) for most metabolites, but the profile showed clear separation by provenance. The contents of two alkyl coumarates, reported for the first time in silver birch leaf waxes, displayed differences among the provenances. Correlations between the surface secondary metabolites and damage by insect herbivores suggest an association between the surface compounds studied and herbivore resistance. Altogether, the contents of leaf surface secondary metabolites varied strongly among the silver birch genotypes, and the profile varied clearly among the provenances.