Clive Ronson, Professor of Genetics at the University of Otago, is an international authority on Rhizobium genetics.
His early study (at the DSIR) of mutants of dicarboxylate transport genes focused attention on 4-carbon dicarboxylic acids as the energy source that plants supply to the bacterium in rhizobial nitrogen fixation, and significantly altered understanding of the molecular events occurring during symbiosis. Stemming from this work (and perhaps his most important discovery) was the first two-component regulatory system in bacteria. These systems, in which an environmental stimulus is sensed by one component in the bacterial cell and passed on to a second component, are now recognised as the major way in which bacteria sense their environments. More recently, Professor Ronson and his students discovered and made an extended study of ‘symbiosis islands’ in Rhizobium bacteria, demonstrating the horizontal transfer of these genetic elements during the evolution of plant-bacterial symbiotic systems.
All of these were published in the Proceedings of the National Academy of Sciences, and have been both highly cited and recognised as major contributions to their field.
He has also made significant contributions, nationally and internationally, as a consultant and advisor, for example as a member of the former Interim Assessment Group on field trials and release of genetically modified organisms, and as a scientific adviser to ERMA New Zealand.