Microbiology & Immunology, University of Otago
‘Comparative and Functional Genomics of the Lotus Microsymbiont Mesorhizobium japonicum R7A’Symbiotic mesorhizobia are soil bacteria which have coevolved with diverse integrative and conjugative elements that confer the capacity for nitrogen-fixing symbiosis with legumes (ICESym). The isolate Mesorhizobium japonicum R7A is a model mesorhizobial symbiont of plants in the Loteae tribe of legumes, including the model plant Lotus japonicus Gifu. Wildtype M. japonicum R7A (R7AWT) carries the symbiosis island ICEMlSymR7A, and a derivative strain cured of the ICESym, M. japonicum R7ANS (R7ANS), has previously been developed. Through acquisition by horizontal transfer of different ICESyms, R7ANS is conferred a symbiotic host-range dependent on the specific ICESym it harbours. The rhizosphere is the zone of influence that surrounds the roots of a plant in the soil. The rhizosphere effect is the change in the rhizosphere affected by a growing plant on the soil and the microbiota therein. Research suggests that the rhizosphere effect of plants is a directed process that may actively shape microbial communities. Little is known about the growth of R7AWT or R7ANS in the rhizosphere of L. japonicus or Arabidopsis thaliana, or what effect the ICEMlSymR7A has on competition therein. Here I present comparative and functional genomic research on the basis of ICESym host range and R7A rhizosphere competition.