Genetic diversity of Xanthomonas phaseoli p v. manihotis populations using rep-PCR and VNTR molecular markers

Diversidade genética de populações de Xanthomonas phaseoli pv. manihotis em mandioca por meio de marcadores rep-PCR e VNTRs

Abstract

The objective of this work was to evaluate the genetic diversity of Xanthomonas phaseoli p v. manihotis (Xpm) from eight populations from five cassava producing states in Brazil, through the rep-PCR (BOX-PCR and ERIC-PCR) and variable number of tandem repeat (VNTR) markers. Cassava leaves with symptoms of cassava bacterial blight were collected in eight municipalities, and the Xpm isolates were identified by amplification with primers specific for these isolates. The identity of the Xpm isolates was confirmed with the BOX-PCR, ERIC-PCR, and VNTR markers. The observed selection pressure, together with the mode of reproduction and the mechanisms that increase genetic variability, allows of the pathogen populations to adapt according to microclimate variation, contributing to a differentiated reproductive success. ERIC-PCR and VNTRs are the best markers for evaluating the genetic variability in the eight studied Xpm populations. However, ERIC-PCR is the marker that best separated the groups by population and presented a higher similarity between the isolates of the same population. The study of the genetic diversity of Xpm is key to improve disease monitoring and management strategies in cassava crops.

Index terms:
Manihot esculenta ; bacterial blight; DNA markers; genetic diversity