title: Inheritance patterns of phenolics in F1, F2, and back-cross hybrids of willows: implications for herbivore responses to hybrid plants.
abstract: The aim of this study was to determine the inheritance pattern of phenolic secondary compounds in pure and hybrid willows and its consequences for plant resistance to leaf-feeding insects. F1, F2, and back-cross hybrids along with pure species were produced by hand pollination of pure, naturally-growing Salix caprea (L., Salicaceae) and S. repens (L.) plants. Leaf concentrations of condensed tannins and seven different phenolic glucosides were determined by using butanol-HCI and HPLC analyses. Insect herbivore leaf damage was measured on the same leaves as used for chemical analyses. We found hybrids to be approximately intermediate between the parental species: S. caprea with high levels of condensed tannins and no phenolic glucosides. and S. repens with low levels of condensed tannins and high levels of phenolic glucosides. We also found a negative correlation between concentrations of condensed tannins and phenolic glucosides, suggesting a trade-off in production of these two substances. F2 hybrids and the hybrid back-crossed to S. caprea were significantly more damaged by insect herbivores than the parental species and the F1 hybrid, indicating reduced resistance and possibly a selective disadvantage for these hybrid categories.
authors.affiliation: Department of Animal Ecology, Swedish University of Agricultural Sciences, 901 83 Umeå, Sweden. per.hallgren@szooek.slu.se
authors.forename: Per
authors.initials: P
authors.lastname: Hallgren
authors.forename: Arsi
authors.initials: A
authors.lastname: Ikonen
authors.forename: Joakim
authors.initials: J
authors.lastname: Hjältén
authors.forename: Heikki
authors.initials: H
authors.lastname: Roininen
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D005247:Feeding Behavior; D006824:Hybridization, Genetic; D007313:Insecta; D010636:Phenols / Q000032:analysis* / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry; D032108:Salix / Q000737:chemistry* / Q000235:genetics*; D013634:Tannins / Q000032:analysis* / Q000235:genetics* / Q000494:pharmacology
chemical_list: D010636:Phenols; D013634:Tannins