Clarifying the taxonomy of the causal agent of bacterial leaf spot of lettuce through a polyphasic approach reveals that Xanthomonas cynarae Trébaol et al. 2000 emend. Timilsina et al. 2019 is a later heterotypic synonym of Xanthomonas hortorum Vauterin et al. 1995

First report of bacterial leaf spot of Hydrangea in retail nurseries in Belgium caused by strains assigned to a new Xanthomonas hortorum clade

“…The Hydrangea leaf spot isolates were assigned to a new clade in the gyrB ‐based phylogeny (Fig. 3 ) of X. hortorum and clearly distinct from any of the existing pathovars in the species (Morinière et al., 2020). Further analysis using whole genome sequences and ANI values is ongoing to determine whether it should be considered a new Xanthomonas species.…”

“…GenBank accession numbers of the partial gyrB sequences of Xanthomonas isolates obtained in this study are shown in Table1. The Hydrangea leaf spot isolates were assigned to a new clade in the gyrBbased phylogeny (Fig.3) of X. hortorum and clearly distinct from any of the existing pathovars in the species(Morinière et al, 2020). Further analysis using whole genome sequences and ANI values is ongoing to determine whether it should be considered a new Xanthomonas species.Pathogenicity was verified on H. arborescens and H. quercifolia by pressurised spray inoculation of the leaves with a suspension of 10 8 cfu/ml of each strain in PB in three replicates and with PB as negative control.…”

Trends in Molecular Diagnosis and Diversity Studies for Phytosanitary Regulated Xanthomonas

“…Other molecular markers, such as CRISPRs that are, however, not widely distributed with the genus Xanthomonas, could be useful for specific taxa. Genome-based methods are now the gold standard to accurately study Xanthomonas diversity and refine the taxonomy of groups, the contours of which were not precisely defined, as was the case for the species X. cynarae, X. gardneri, and X. hortorum [13].…”

“…Most of the species are of phytosanitary concern since they are causal agents of diseases with a global impact on seed, plant and food trade, being responsible for important economic and environmental losses [6,7]. The contours of this genus have tremendously evolved with the transfer of species into related genera (e.g., [8,9]), the description of novel species [10,11] and taxonomic rearrangements leading to synonymy of taxa [12][13][14][15].…”

Complete or High-Quality Draft Genome Sequences of Six Xanthomonas hortorum Strains Sequenced with Short- and Long-Read Technologies

“…The genetic relatedness of the Xanthomonas hortorum species-level clade (slc) was established by Parkinson et al using partial gyrB gene sequences ( 1 ). The most recently updated taxonomy of the clade ( 2 ) includes seven pathovars of X. hortorum (cynarae, gardneri, carotae, hederae, pelargonii, taraxaci, and vitians type B) ( 1 – 3 ).…”