Respuesta :
Axonomic proposals are made: emendations of the descriptions of X. citri, X. phaseoli and X. axonopodis, to encompass the strains of PG I, PG III and PG IV, respectively; and reclassification of X. perforans and X. alfalfae as X. euvesicatoria and emendation of the description of X. euvesicatoria to encompass all strains of PG II.
Strains:
- The bacterial blight that affects anthurium is caused by Xanthomonas axonopodis pv. dieffenbachiae (Xad), which is classified as an A2 quarantine organism by EPPO. However, a number of strains go by the name Xad. A polyphasic taxonomic approach was used to evaluate 25 Xad strains and 88 phylogenetically related strains, including Xanthomonas type strains and representatives of additional pathovars.
- The type strain of X. axonopodis clustered into a fourth group after multilocus sequencing analysis of seven genes, while strains isolated from Dieffenbachia, Philodendron, and Anthurium fell into three phylogenetic groups (PG I, II, and III) (PG IV). X. citri subsp. citri, X. citri subsp. malvacearum, X. fuscans subsp. fuscans, and X. fuscans subsp. aurantifolii type strains were included in PG I. X. euvesicatoria, X. perforans, X. alfalfae subsp. alfalfae, and X. alfalfae subsp. citrumelonis type strains were included in PG II. The X. phaseoli type strains were part of PG III.
- Based on average nucleotide identity values, DNA-DNA hybridization data, and behavioral traits, it was demonstrated that each PG represented a single species. As a result, the strains known as Xad are from PG I, PG II, and PG III, not X. axonopodis (PG IV). The following taxonomic suggestions are made: reclassification of X. perforans and X. alfalfae as X. euvesicatoria; and emendation of the description of X. euvesicatoria to encompass all strains of PG II. X. citri, X. phaseoli, and X. axonopodis have their descriptions modified to include the strains of PG I.
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