Dr Ann Hirsch, University of California

Dr Ann Hirsch of the University of California will give a seminar entitled "Plant Growth-Promoting Burkholderia species: the good, the bad, and the ugly".

The genus Burkholderia is composed of bacteria with commensal, pathogenic, or symbiotic lifestyles that were formerly in the RNA homology Pseudomonas group II. Recently, more attention has been paid to the symbiotic Burkholderia species, especially those that establish nitrogen-fixing nodules on legumes. Genomic analysis of Burkholderia tuberum and B. phymatum has revealed the presence of nif and nod genes, which are required for symbiotic nitrogen fixation and effective nodulation of papilionoid legumes and siratro (Bt) and mimosoid legumes (Bp).

Nonetheless, because some Burkholderia are serious pathogens on humans and domestic animals, the potential use of Burkholderia species as inocula has generated concern. To this end, we utilised various bioassays to demonstrate unequivocally that plant-associated Burkholderia species from South Africa, Australia, and Brazil are not pathogenic. We also searched the sequenced genomes for genes important for virulence.

In addition, the use of various concatenated housekeeping gene sequences result in phylogenetic trees that clearly separate the symbiotic and plant-beneficial species from the pathogenic ones.

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