Analysis of the worldwide diversity ofXanthomonas hortorumpv.carotae, the agent of bacterial blight of carrot, reveals two distinct populations

Abstract

AbstractXanthomonas hortorumpv.carotaeis a pathogen responsible for the bacterial blight of carrot. While it infects carrot fields worldwide, its diversity remains unknown. Here, we validated by PCR the identification asX. hortorumpv.carotaeof most of the strains isolated from carrot symptoms. We study their diversity by sequencing seven housekeeping genes. The analysis confirmed the identity of most of the strains previously identified asX. hortorumpv.carotaeand highlighted the presence of two clusters inside the pathovarcarotae. The 18 non-X. hortorumpv.carotaehave been identified asXanthomonasfrom other species. As theX. hortorumpv.carotaestrains clustered only in two groups by this analysis, a new MLVA scheme was developed. It allowed to validate the subclusteration in two groups and observe diversity among them. At the same times based on this study and data from the literature, we proposed the strain CFBP 7900 as the neopathotype strain of the pathovar. The strain should replacement the holopathotype strain CFBP 4997, as it is no longer available in international collection.