Fungal-bacterial interactions in wetwood of British broadleaf trees

Bacterial wetwood is a common feature of living trees, characterised by patches of saturated wood in the centre of trunks colonised by highly abundant bacteria. In many tree species it is asymptomatic and apparently harmless, but almost nothing is known about how, when and why it forms. The interior of trees is usually a fungal-dominated

habitat, and wetwood provides an intriguing exception where it seems that bacteria are dominant. Recent work has indicated distinct communities of both fungi and bacteria in wetwood, but their functions and interrelationships remain unknown. Wetwood is of ecological importance, as it remains an unknown factor in tree

health and carbon sequestration, and of economic importance as it negatively affects the value of the wood. Understanding wetwood will also assist arborists and other tree professionals in making management decisions. This PhD project will investigate the occurrence, distribution and ecology of wetwood using a combination of

fieldwork, culturing, molecular ecology, bioinformatics and statistics. It will explore the microbial communities associated with wetwood and how they form and function. The project will involve hands-on experience with community profiling using next-generation sequencing and metabolite profiling through mass spectrometry. You

will therefore be equipped with a valuable skillset, much sought after by employers. We anticipate that the project will develop in five stages: 1. A survey of felled and recently fallen trees to identify different tree taxa with symptoms of wet wood. 2. Sampling wetwood from those trees for culturing and community analysis of both fungi and bacteria.

3. Physiological and metabolic characterisation of key bacteria isolates. 4. Mapping and model routes of water ingress from possible entry points to wetwood patches within the trunk. 5. Microcosm experiments to examine key interspecific interactions in detail.