Burkholderia semiarida sp. nov. and Burkholderia sola sp. nov., two novel B. cepacia complex species causing onion sour skin.

Two putative novel Burkholderia cenocepacia lineages found in the semi-arid region of north-east Brazil causing onion sour skin were studied using genomic approaches to determine their taxonomic position. Four strains belonging to one novel lineage (CCRMBC16, CCRMBC33, CCRMBC74, and CCRMBC171) and one strain (CCRMBC51) belonging to another novel lineage had their whole genome sequenced to carry out taxogenomic analyses. The phylogenomic tree built using the type (strain) genome server (TYGS) clustered the strains CCRMBC16, CCRMBC33, CCRMBC74, and CCRMBC171 into the same clade, while grouped the strain CCRMBC51 separately. Average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) analysis showed values above 99.21 % and 93.2 %, respectively, among the strains CCRMBC16, CCRMBC33, CCRMBC74, and CCRMBC171, while ANI and dDDH values between these strains and the strain CCRMBC51 were below 94.49 % and 56.6 %, respectively. All these strains showed ANI and dDDH values below 94.78 % and 58.8 % concerning type strains of the B. cepacia complex (Bcc) species. The phylogenetic maximum likelihood tree constructed based on the multilocus sequence analysis of core genes (cMLSA) clustered the strains CCRMBC16, CCRMBC33, CCRMBC74, and CCRMBC171 and the strain CCRMBC51 in two exclusive clades, which did not cluster with any known species of the Bcc. Therefore, combined data from TYGS, ANI, dDDH, and cMLSA demonstrated that the strains represent two novel species of the Bcc, which we classified as Burkholderia semiarida sp. nov. and Burkholderia sola sp. nov., and proposed the strains CCRMBC74T (=IBSBF 3371 T = CBAS 905 T) and CCRMBC51T (=IBSBF3370T = CBAS 904 T) as type strains, respectively.

Genome Sequence of Ralstonia pseudosolanacearum Strains with Compatible and Incompatible Interactions with the Major Tomato Resistance Source Hawaii 7996.

We report here the complete genome sequences of two Ralstonia pseudosolanacearum strains, isolated from the warm northeast region of Brazil. They display divergent (compatible versus incompatible) interactions with the resistant tomato line Hawaii 7996. Polymorphisms were detected in a subset of effector genes that might be associated with these contrasting phenotypes.

Moko Disease-Causing Strains of Ralstonia solanacearum from Brazil Extend Known Diversity in Paraphyletic Phylotype II.

The epidemic situation of Moko disease-causing strains in Latin America and Brazil is unclear. Thirty-seven Ralstonia solanacearum strains from Brazil that cause the Moko disease on banana and heliconia plants were sampled and phylogenetically typed using the endoglucanase (egl) and DNA repair (mutS) genes according to the phylotype and sequevar classification. All of the strains belonged to phylotype II and a portion of the strains was typed as the Moko disease-related sequevars IIA-6 and IIA-24. Nevertheless, two unsuspected sequevars also harbored the Moko disease-causing strains IIA-41 and IIB-25, and a new sequevar was described and named IIA-53. All of the strains were pathogenic to banana and some of the strains of sequevars IIA-6, IIA-24, and IIA-41 were also pathogenic to tomato. The Moko disease-causing strains from sequevar IIB-25 were pathogenic to potato but not to tomato. These results highlight the high diversity of strains of Moko in Brazil, reinforce the efficiency of the egl gene to reveal relationships among these strains, and contribute to a better understanding of the diversity of paraphyletic Moko disease-causing strains of the R. solanacearum species complex, where the following seven distinct genetic clusters have been described: IIA-6, IIA-24, IIA-41, IIA-53, IIB-3, IIB-4, and IIB-25.