Two annual legume species and their selection of nodule occupants

Abstract

With its intensive animal production, New Zealand relies heavily on legume and ryegrass dominated pastures. Legumes in association with their rhizobial symbionts fix nitrogen and provide high quality forage. Little is known about naturalised rhizobia strains in New Zealand soils except that they are noted to be at reasonably high levels (Lowther and Kerr 2011). It is well established that some rhizobial strains nodulate multiple genera and species of legumes, while others might nodulate only one plant species. This work sets out to determine whether naturalised rhizobia resident in a pasture soil will nodulate the two different annual legume species tested. ERIC (enterobacterial repetitive intergenic consensus) PCR is a method used to determine bacterial strain diversity (Versalovic et al. 1991). It can be used to distinguish even closely related Rhizobium strains and has been used in numerous studies to determine nodule occupancy (Nangul et al. 2013; Youseif et al. 2014). The aim of this work was to discern if two different annual legume species were nodulated by naturalised strains and whether they were selective for a particular rhizobia strain.