Genetic variation and additive inheritance of resistance of Eucalyptus globulus to possum browsing

Browsing of plantation seedlings and saplings by herbivores is a major problem for the successful establishment and management of plantations in Australia. The use of natural plant resistance in deployment or breeding programs may be an option for reducing such browsing. We assessed the variation in resistance of Eucalyptus globulus races, provenances, and families to browsing by the brushtail possum (Trichosurus vulpecula) in common environment field trials and captive feeding trials. There were significant genetic based differences between provenances of E. globulus in the extent to which they were browsed, and sideroxylonals, a group of defensive plant chemicals, were the most important determinant of coppice foliage intake by possums. Investigations of the resistance of intra- and inter-race F1 hybrids indicated that resistance of E. globulus to possum browsing is additively inherited. These results suggest there is potential to deploy genotypes with greater resistance through appropriate selection and breeding.