Two Burkholderia strains from nodules of Dalbergia odorifera T. Chen in Hainan Island, southern China

Two Burkholderia strains 8111 and 8201 were isolated from root nodules of Dalbergia odorifera, an endemic woody legume in southern China. Phylogenetic analysis of 16S rRNA gene and 16S-23S gene intergenic spacer (ITS) showed that these two bacterial strains were closely related to Burkholderia cepacia and they were also similar in carbon source utilization using Biolog GN2 plate tests. The DNA G+C content of strains 8111 and 8201 were 65.8 and 65.5 mol%. Inoculation tests demonstrated that both strains 8111 and 8201 formed functional root nodules in their original host D. odorifera, and significantly enhanced plant growth (as measured by plant biomass and nitrogen content), compared to the no-inoculated control plants. Sequencing of 16S rRNA gene in nodules of D. odorifera seedlings inoculated with strains 8111 and 8201 confirmed their identity. However, these two strains did not induce root nodulation in Acacia auriculiformis and Erythrophleum fordii. This implies that the nodulation capacity between Burkholderia strains 8111 or 8201 and their legume hosts may be specific. Our results show that both Burkholderia strains 8111 and 8201 are able to form functional nodules on D. odorifera and are potentially beneficial inoculants for seedling propagation to be used in large scale D. odorifera plantations.