Professor Peter Young, University of York seminar

Professor Peter Young, University of York will give a seminar entitled "Rhizobium population genomics and the nature of bacterial species" at the James Hutton Institute.

It is becoming apparent that the processes by which bacteria adapt are actually very different from those that are implicit in the classical view of microbiology and we need to describe bacterial diversity in a different way.

Thanks to a long history of diversity studies, our knowledge of rhizobia can make a major contribution to this broader picture. The host range is an obvious phenotype of ecological significance but we know that the relevant genes are usually on a plasmid or genomic island in rhizobia, and have a history of transfer into different genetic backgrounds. This has led to the definition of symbiovars which cut across the species that are defined by core genes.

I will illustrate this with our own recent work on the population genomics of Rhizobium leguminosarum. We have partially sequenced the genomes of 72 isolates from a single population, half being symbiovar viciae and half trifolii. We identify five cryptic species within this population that show little gene flow between them for core genes but share adaptive accessory modules like the symbiosis genes. Hence the species, defined by core genes, is not a reliable indicator of ecological adaptation.

Peter Young's PhD thesis at the University of Cambridge was on the population genetics of the water flea, Daphnia magna. He then spent three years at the State University of New York at Stony Brook studying natural selection acting on the edible mussel and a year at the University of Sussex working on an amylase polymorphism in Drosophila.

His first permanent position was at the John Innes Institute in Norwich, where he started out on the quantitative genetics of peas, but gradually shifted to the population genetics of the symbiotic rhizobia on the roots.

Twenty years ago, he took up the Chair of Molecular Ecology at the University of York, where he continued his interest in the diversity and evolution of rhizobia but was also persuaded to take on another important group of root symbionts, the arbuscular mycorrhizal fungi. Since then, his group has used a variety of molecular approaches to describe and understand natural genetic diversity, and has been involved in the genomics of both rhizobia and mycorrhizas.

This seminar will take place at the James Hutton Institute Dundee and will be broadcast live to the Aberdeen site.