Population typing of the causal agent of cassava bacterial blight in the Eastern Plains of Colombia using two types of molecular markers

Abstract

BackgroundMolecular typing of pathogen populations is an important tool for the development of effective strategies for disease control. Diverse molecular markers have been used to characterize populations of Xanthomonas axonopodis pv. manihotis (Xam), the main bacterial pathogen of cassava. Recently, diversity and population dynamics of Xam in the Colombian Caribbean coast were estimated using AFLPs, where populations were found to be dynamic, diverse and with haplotypes unstable across time. Aiming to examine the current state of pathogen populations located in the Colombian Eastern Plains, we also used AFLP markers and we evaluated the usefulness of Variable Number Tandem Repeats (VNTRs) as new molecular markers for the study of Xam populations.ResultsThe population analyses showed that AFLP and VNTR provide a detailed and congruent description of Xam populations from the Colombian Eastern Plains. These two typing strategies clearly separated strains from the Colombian Eastern Plains into distinct populations probably because of geographical distance. Although the majority of analyses were congruent between typing markers, fewer VNTRs were needed to detect a higher number of genetic populations of the pathogen as well as a higher genetic flow among sampled locations than those detected by AFLPs.ConclusionsThis study shows the advantages of VNTRs over AFLPs in the surveillance of pathogen populations and suggests the implementation of VNTRs in studies that involve large numbers of Xam isolates in order to obtain a more detailed overview of the pathogen to improve the strategies for disease control.

The role of type III effectors from Xanthomonas axonopodis pv. manihotis in virulence and suppression of plant immunity

“…However, the use of resistant varieties seems to be the most efficient method to control CBB (Verdier et al ., ). In order to deploy durable resistance, it is important to understand the population genetics of the pathogen (Restrepo et al ., ; Trujillo et al ., ) and the virulence factors that are crucial for the pathogen to cause disease (Lopez and Bernal, ). Ideally, for plant breeding approaches, resistance should be targeted against T3Es that are broadly conserved in the pathogen and that are crucial for bacterial fitness (Boyd et al ., ).…”

“…In Xam , previous work has focused on the population dynamics (Restrepo et al ., ; Trujillo et al ., ), strain characterization in cassava cultivars (Restrepo et al ., ; Wydra et al ., ) and the mapping of expressed sequence tags (ESTs) associated with resistance (Lopez et al ., ). However, the identification of Xam pathogenicity factors is an important step towards the development of new strategies against CBB.…”

Draft Genome Sequences of Two Xanthomonas vesicatoria Strains from the Balkan Peninsula

“…Combined with the draft genome sequence of the New Zealand strain X. vesicatoria ATCC 35937, which was isolated from Lycopersicon lycopersicum ( 11 ), these genomic resources will aid in the development of new diagnostic tools, such as multilocus VNTR analyses (MLVA), which have been proven to be powerful tools for studying bacterial phytopathogen populations ( 12 – 15 ). In addition, these genome sequences may give new insight into the pathogen-host interaction.…”

TAL Effector Repertoires of Strains of Xanthomonas phaseoli pv. manihotis in Commercial Cassava Crops Reveal High Diversity at the Country Scale

“…In Colombia, CBB was first described in 1971 [ 35 ]. More recently, Trujillo and coworkers described the genetic structure of Xpm populations in the most prominent cassava production regions, showing high susceptibility of the most common cultivars grown and a complex pathogen population structure in some of these regions [ 49 , 50 ].…”