Nevertheless, the values of the Mexican population are quite low, which may indicate that some recombination occurs. BIBW2992 order Recombination
has had an important role in the long-term evolution of B. cenocepacia and it was also found among strains from different locations [20, 32]. Most likely, the efficiency of genetic exchange mechanisms, due to BCC inherent genomic plasticity, together with ecological factors, play a crucial role. The use of a common MLRT scheme for both B. cenocepacia IIIB and BCC6 group allowed to compare their genetic variability, relatedness, and population structure also at interspecific level. B. cenocepacia IIIB and BCC6 populations shared identical alleles but not the same RTs. In the UPGMA tree, where the genetic similarities
between the restriction profiles of both B. cenocepacia IIIB and BCC6 group were represented, the isolates were grouped into two main clusters (clusters I and II) corresponding to their taxonomic status and eBURST clonal complexes; i.e., LXH254 supplier cluster I for B. cenocepacia IIIB and RT-4-complex, and cluster II for BCC6 group and RT-104-complex. Within each cluster, the occasional presence of few isolates belonging to the other BCC species is not surprising since BCC6 and B. cenocepacia IIIB are closely related, and indeed BCC6 was previously included in the B. cenocepacia species. UPGMA performed with only the isolates included in the RT-4 and RT-104 clonal complexes gave rise to a dendrogram showing two clusters exactly corresponding to them (data not shown), confirming the Ralimetinib correspondence between eBURST and UPGMA grouping. Finally, the finding of a clear relationship between grouping and maize cultivar suggests that maize cultivars could influence rhizosphere bacterial diversity probably due to the different chemical composition of root exudates. In fact, it is well known that plant root bacterial communities are very sensitive to environmental conditions and are more strongly
influenced by plant species Non-specific serine/threonine protein kinase and different cultivars rather than by other environmental factors such as soil type and agricultural practices [46–49]. Conclusions In conclusion, our data demonstrate a wide dispersal of certain B. cenocepacia IIIB and BCC6 isolates in Mexican and Italian maize rhizospheres. Despite the clear relationship found between the geographic origin of isolates and grouping, identical RTs and closely related isolates were observed in geographically distant regions. The differences in rhizosphere habitats and/or maize varieties between Italy and Mexico may result in certain selective pressure which may preferably promote some genotypes within each local microbial population, favouring the spread of a single clone above the rest of the recombinant population.