Ash Tree Research  

Dr Estrella Luna Diez is continuing to work on a project aiming to understand the impact of mixed species forests in the resistance of ash trees to ash dieback disease. Funded by Gatsby and a panel of scientific Societies Dr Luna Diez led a summer project (2019) where 5 undergraduate students surveyed over 7,000 trees in the Norbury Estate. This project has identified tree species that drive enhanced resistance and susceptibility to the disease.  These results could inform planting strategies to increase resilience of future forests. Estrella's new research project MEMBRA will also bring new research around ash dieback disease.

Dr Sabrine Dhaouadi's research includes several approaches to be employed for the establishment of robust pathosystem models that underpin a detailed examination of infection and disease progression. This research will be applied to the main tree diseases in the UK: acute oak decline, bacterial canker of cherry and ash, bleeding canker of horse chestnut, diseases that had emerged in both UK and Europe within the last 20 years.

PhD Students 

Kieran Clark:
Supervisors: Prof. Pola Goldberg Oppenheimer (Chem Eng), Dr Estrella Luna Diez (Bio)
Year of Study: First
PhD Draft Title: Study and Fabrication of Rapid Engineered Spectroscopic Technology (FoRESTech) for Identification of Filamentous Pathogens in Leaves
Info: This project aims to use the non-destructive and versatile method of Raman spectroscopy as a diagnostic tool to probe biomolecular changes to the surface structure of the leaf during the course of ash dieback and oak powdery mildew infections. A microscopic survey of the surface of the leaf is conducted and areas of non-vein, secondary vein and primary vein tissues are identified. An 830nm laser is used to probe these tissue types and Raman spectra are formed for the healthy and infected classes for ash and oak leaves both grown in ambient and elevated carbon dioxide environments. An initial study, conducted for a healthy oak leaf grown in an ambient carbon dioxide environment, indicated spectral similarity between all tissue types with the primary vein tissue being the most dissimilar. The major differences between the tissue type spectra were identified between the pectin region at 800-900cm-1; the carotenoid peaks at 1158cm-1 and 1527cm-1; and the lignin peak at 1610cm-1. The produced spectra will be further compared in different ways using advanced computational methods to identify spectral differences. These differences will be attributed to either biomarkers of disease, structural differences between growth conditions or further tissue type differences. Finally, a handheld Raman spectrometer will be developed to identify these biomarker-related spectral changes to diagnose these diseases in the field.

Katherine Hinton - 
Supervisors: Professor Robert Jackson (Bio) Dr Megan McDonald (Bio), Professor Richard Buggs (Kew Gardens)
Year of Study: First
PhD draft title: Examining risk of new disease outbreaks in a diseased population using ash as a model
InfoPseudomonas savastanoi pv. fraxinii causes canker disease in ash trees, and although it is widespread in the UK, the severity of the disease is relatively low. Why this is the case is not understood and there could be potential for severity to increase in trees weakened by other diseases like ash dieback or pest attack like Emerald Ash Borer. This project therefore aims to develop new tools to study this pathosystem and examine whether there is any potential threat of bacterial disease outbreaks in ash.


Jiaqi Wei:
Supervisors: Prof Robert Jackson (Bio), Dr Graeme Kettles (Bio)
Year of study: First
PhD (draft) title: Evaluating the threat of Xylella on UK trees 
Info: Xylella fastidiosa is a bacterium that is endemic to central America. It is an established pathogen in the US and is a recently emerging pathogen causing devastating disease in southern Europe. Presently, they are limited to Italy, Portugal, Spain and France, but detection of infected plants has been found in other countries in Europe triggering control and eradication procedures. Tree species like ash and oak have also been observed with Xylella infections in Europe, highlighting the wide host range of the pathogen. 
There is considerable concern around the potential threat to the UK’s horticulture and ecosystem, particularly to trees, should Xylella establish in the country and thus it is important that investment is made to fully understand the threat the pathogen poses. This will help with identifying the potential hosts for the pathogen and whether any resistance exists in the plant population. It will also help with identification and monitoring as well as considering the risk of widespread disease spread.