Evaluation of necrosis formation as a robust tool in tree resistance breeding

Scientific studies often evaluate tree resistance using bioassays where trees are artificially infected by a pathogen, and the resistance is evaluated based on the length of the necrosis that is formed in the host tissue.

However, the rate and extend of necrosis formation may be influenced by the fungi that ubiquitously colonize the surfaces and internal spaces of all trees.

These fungi are biologically active and may interact directly with the invading pathogen or influence the tree defensive responses.

Because the fungal communities are strongly dependent on the environment their interference can obscure the usefulness necrosis formation as an indicator of genotypic resistance in biotests, increasing the risk for erraneous decisions in tree breeding programs. The project will critically examine the usefulness of necrosis-based bioassays.

Using metagenomics approches, network analysis and phenotype microarrays, we will characterize the fungal communities in and outside the necrotic lesions, evaluating both the diversity and functional traits of these communities.

Using a participatory approach, we will then evaluate the usefulness of necrosis-based bioassays for resistance breeding. The project is carried out as an international collaboration and delivers new knowledge and practical solutions.

It is particularly timely now because of the increasing threat of new diseases in the economically and ecologcially important Scots pine forests.