MEASUREMENT OF THE GENETIC DIVERSITY IN XANTHOMONAS AXONOPODIS PV. MANIHOTIS WITHIN DIFFERENT FIELDS IN COLOMBIA
S RESTREPO1,2, C VELEZ2 and V VERDIER1-2
1Centro Internacional de Agricultura Tropical (CIAT), Biotechnology Research Unit, AA 6713, Cali, Colombia, and 2Institut Français de Recherche Scientifique pour le développement en Coopération (ORSTOM), BP5045, 35032 Montpellier, France
Background and objectives
Cassava Bacterial Blight (CBB) is a widespread disease affecting cassava (Manihot esculenta Crantz) crop. It is caused by Xanthomonas axonopodis pv. manihotis (Xam), that can induce a wide variety of symptoms including angular leaf spots, blight, gum exudation, wilting, stem cankers and die-back. To guide the selection and deployment of resistant genotypes, it is essential to characterize the pathogen population structure. Genetic diversity of Xam was mainly characterized by RFLP analyses using a Xam plasmidic probe (pthB) related to the avr-pth gene family. The RFLP/pthB analysis has shown to be more discriminative than RFLP with genomic Xam probes or ribotyping . The distribution of pathogen diversity among different agroecosystems in Colombia was conducted during 1995, showing that a geographical differentiation of pathogen populations exists . Specific RFLP haplotypes were characterized in each of the ecological zones studied . Our goal was to continue the analysis of Xam population structures in Colombia by examining the variation and distribution of the pathogen in fields located in each of the ecological zones previously studied.
Materials and Methods
Results and conclusions