Nodulation and effective nitrogen fixation of Macroptilium atropurpureum (siratro) by Burkholderia tuberum, a nodulating and plant growth promoting beta-proteobacterium, are influenced by environmental factors

Backgroundandaims BurkholderiatuberumSTM678 T was isolated from a South African legume, but did not renodulate this plant. Until a reliable host is found, studiesonthisand other interesting beta-rhizobia cannot advance. We investigated B. tuberum STM678 T ’s ability to induce Fix + nodules on a small-seeded, easy-topropagate legume (Macroptilium atropurpureum). Previous studies demonstrated that B. tuberum elicited either Fix - or Fix + nodules on siratro, but the reasons for this difference were unexplored. Methods Experiments to promote effective siratro nodule formation under different environmental conditions were performed. B. tuberum STM678 T ’s ability to withstand high temperatures and desiccation was checked as well as its potential for promoting plant growth via mechanisms in addition to nitrogen fixation, e.g., phosphate solubilization and siderophore