Improvement of the specific detection of Xanthomonas phaseoli pv. manihotis based on the pthB gene

ABSTRACT. Modifications were made in the PCR conditions aiming to overcome the problem of non-amplification of the Xanthomonas phaseoli pv. manihotis (Xpm) fragment, using the primer pair XV / XK described in the literature. The objective of this study was to propose changes in the primers already described (XV / XK_MOD) and validate the use of these new primers in identifying Xpm. The validation procedure was carried out with the primer pair XV and XK_MOD, using different strains of Xpm, other plant pathogenic and endophytic bacteria genera and one isolate of X. phaseoli pv. passiflorae. As a control, additional reactions were conducted in multiplex with the universal primers for the 16S rRNA gene of the bacteria together with XV / XK and XV / XK_MOD. Using the forward primer (XV) described in the literature together with the modified reverse primer (XK_MOD), it was possible to achieve amplification from DNA extracted from in vitro cultures and from infected tissue, but no amplification was noticed for the primer pair described in the literature, confirming the effectiveness of the proposed modification.