Professor Allan Downie is an expert in the area of rhizobial-legume symbioses focussing on the genetics of signalling between the two symbiotic partners. He has been a research leader at the John Innes Centre in Norwich since 1981, serving on its management board and acting as Chair of Faculty from 2005 to 2012. Since then he has been an Emeritus Fellow at the John Innes Centre and holds an honorary professorship at the University of East Anglia. He has over 200 research publications in reviewed journals and has published several authoritative reviews in the area of symbiotic nitrogen fixation in legumes.
His research has focussed on the signalling that occurs between rhizobia during the initiation of the process that leads to rhizobial infection of legume roots and the induction of nodules in which nitrogen fixation occurs. He identified the Rhizobium nodulation (nod) genes required for the synthesis of the lipochitin oligosaccharide signals, which are required to activate infection and nodule morphogenesis. During this work, he identified founding examples of classes of proteins including ATP-dependent (ABC) membrane transporters, condensing enzyme and a group of acetyl transferases. One of the nodulation proteins was a secreted protein that forms cation selective channels, giving him the insight that ion fluxes across the plant root-hair membrane were critical for rhizobial infection and this together with the work of others led to a recognition that there were two types of calcium signal activated by rhizobia, a calcium influx and an oscillation of calcium originating from the perinuclear membrane. This led to his development of a calcium-based nodulation signalling pathway and he has been involved in the identification of many of the signalling proteins in this pathway. More recently he has focussed on plant proteins required for initiation of infection by rhizobia, a process that requires rhizobial attachment and localised activation of signalling. This induces a plant pectate lyase that causes localised plant cell wall degradation and he has also been involved in the identification of several plant proteins that rearrange the plant cytoskeleton in readiness for the development of plant-made infection tunnels called infection threads.
Allan Downie was elected as a member of Academia Europaea in 2016.