Phylogenetic and molecular studies of the populations of Phytophthora ramorum, lineages EU1 and EU2, in Ireland and gene expression during infection of Larix spp

• Main Author: De la Mata Sáez, Lourdes
• Format: Dissertation
• Language: English
• Published: Queen's University Belfast 2016

Phytophthora ramorum is causing major damage to the economy and the natural ecosystems of the countries where it is found. There are four different lineages of P. ramorum: NA1, NA2, EU1 and EU2. EU2 has only been found in Northern Ireland and southwest coast of Scotland The populations EU1 and EU2 on the island of Ireland were studied. The results showed that all the isolates collected from the Republic of Ireland were EU1, as In the rest of Europe and the majority of the Isolates from Northern Ireland and Scotland were EU2. Further study resulted in phylogenetic trees that suggested that the EU1 population in the Republic of Ireland is the result of multiple introductions brought by plant trade from Europe. Additionally! the EU2 population in Northern Ireland is the results of a single Introduction, probably brought from Asia, and then spread across the country. The interaction of P. ramorum with its most affected host In the UK, larch, was studied. High throughput sequencing was performed with Illumlna 2000 Hiseq in European and Japanese larch trees infected with the lineages EU1 and EU2. This showed a larger number of general defence genes activated in European larch against the pathogen, along with a larger number of Inactivated genes In Japanese larch, supporting the idea that European larch is more resistant to P. ramorum. Some defence molecular pathways were studied, showing that European larch activates more genes in each specific pathway. A selection of genes involved in the different defence pathways were studied showing that the highest peak of plant defence against the pathogen occurs 3 days after the inoculation, suggesting that for the plant It Is important to react quickly in order to survive the pathogen attack.