Assessment of genetic diversity among strains of Xanthomonas campestris pv. manihotis

Verdier, Valérie; Dongo, P.; Boher, Bernard

doi:10.1099/00221287-139-11-2591

Cited by 37 publications

(51 citation statements)

References 22 publications

(18 reference statements)

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“…In previous studies, several molecular markers (repetitive fragment PCR, amplified fragment length polymorphism, and ribotyping) were tested for their utility in characterizing X. axonopodis pv. manihotis populations (3,19,23,24,28). RFLP was found to be the most informative and discriminative technique for assessing the genetic diversity of X. axonopodis pv.…”

Section: Discussionmentioning

confidence: 99%

“…The RFLP technique, using the pathogenicity gene pthB as a probe, is precise and discriminatory in differentiating among X. axonopodis pv. manihotis strains (28). It permitted the description of basic population genetic parameters and processes like geographical differentiation of the X. axonopodis pv.…”

mentioning

confidence: 99%

“…manihotis populations have been characterized by restriction fragment length polymorphism (RFLP) (24,27,28) and virulence variation (20). The RFLP technique, using the pathogenicity gene pthB as a probe, is precise and discriminatory in differentiating among X. axonopodis pv.…”

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confidence: 99%

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Genetic Structure and Population Dynamics of Xanthomonas axonopodis pv. manihotis in Colombia from 1995 to 1999

Restrepo

Vélez

Duque

et al. 2004

Appl Environ Microbiol

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Restriction fragment length polymorphisms (RFLPs) were used to study the population genetics and temporal dynamics of the cassava bacterial pathogen Xanthomonas axonopodis pv. manihotis. The population dynamics were addressed by comparing samples collected from 1995 to 1999 from six locations, spanning four different edaphoclimatic zones (ECZs). Forty-five different X. axonopodis pv. manihotis RFLP types or haplotypes were identified between 1995 and 1999. High genetic diversity of the X. axonopodis pv. manihotis strains was evident within most of the fields sampled. In all but one site, diversity decreased over time within fields. Haplotype frequencies significantly differed over the years in all but one location. Studies of the rate of change of X. axonopodis pv. manihotis populations during the cropping cycle in two sites showed significant changes in the haplotype frequencies but not composition. However, variations in pathotype composition were observed from one year to the next at a single site in ECZs 1 and 2 and new pathotypes were described after 1997 in these ECZs, thus revealing the dramatic change in the pathogen population structure of X. axonopodis pv. manihotis. Disease incidence was used to show the progress of cassava bacterial blight in Colombia during the 5-year period in different ecosystems. Low disease incidence values were correlated with low rainfall in 1997 in ECZ 1.Cassava, Manihot esculenta Crantz, is a starchy root crop that is among the most important tropical foods. About 80% of the cassava produced is consumed in developing countries and constitutes the principal carbohydrate source for more than 500 million people (14). Cassava bacterial blight (CBB) has caused extensive damage to the crop during the past 2 decades (6, 14, 30). The causal agent, Xanthomonas axonopodis pv. manihotis, can induce a wide variety of symptoms, including angular leaf spots, blight, gum exudation, stem cankers, shoot wilt, vascular necrosis, and dieback (15). Resistance, which has been identified in M. esculenta and the wild relative Manihot glaziovii, is thought to be polygenic and additively inherited (9). Molecular markers have been employed to construct a genetic map of the cassava genome consisting of several hundred markers (8). The mapping of CBB resistance has recently been reported both in controlled conditions and in the field (10, 11). Resistance to X. axonopodis pv. manihotis strains is controlled by several quantitative trait loci (QTL) located in different linkage groups, suggesting a specific interaction between the plant and the pathogen. Some of these QTL are specific to one strain, showing the complexity of this host plant-pathogen interaction (10). Since 1983, the entire cassava breeding strategy has been based on improving varieties for different edaphoclimatic zones (ECZs) (1). The ECZs were defined according to the importance of cassava production in that region, climatic conditions, predominant soil type, and pest and disease problems (2). Seven zones exist: ECZ 1, subhumid tropics;...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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Genetic Structure and Population Dynamics of Xanthomonas axonopodis pv. manihotis in Colombia from 1995 to 1999

Restrepo

Vélez

Duque

et al. 2004

Appl Environ Microbiol

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“…A standardized method for CBB resistance screening in cassava germplasm (Maraite et al 1981;Verdier et al 1993;Restrepo and Verdier 1997) was employed. Stems were inoculated as described by Verdier et al (1994).…”

Section: Greenhouse Evaluation Of Disease Resistancementioning

confidence: 99%

“…Yield losses in different areas of Africa and South America may be anywhere between 12% and 90% (Persley 1977;Lozano and Laberry 1982). The variability of Xam, based on pathogenicity and on physiological, biochemical, and (recently) molecular characterization, reveals greater genetic diversity in Latin America than in Africa or Asia (Lozano and Sequeira 1974;Grousson et al 1990;Verdier et al 1993;Restrepo and Verdier 1997;Verdier et al 1998). Genetic studies reveal that CBB was recently introduced to Africa from Latin America and that in Latin America Xarn populations from distinct edaphoclimatic zones (or ecozones) are differentiated (Verdier et al 1993; Restrepo and Verdier 1997;Verdier et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Genetic mapping of resistance to bacterial blight disease in cassava (Manihot esculenta Crantz)

Jorge¹,

Fregene²,

Duque³

et al. 2000

Theor Appl Genet

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Cassava bacterial blight (CBB), caused by Xanthoinonas axonopodis pv. manihotis (Xam), is a major disease of cassava (Manihot esculenta Crantz) in Africa and South America. Planting resistant varieties is the preferred method of disease control. Recent genetic mapping of an F, cross (TMS 30572 x CM 2177-2) led to the construction of the first molecular genetic map of cassava. To better understand the genetics of resistance to CBB, we evaluated individuals of the F, cross for CBB resistance by controlled greenhouse inoculations and visually assessed symptoms on days 7, 15, and 30 days after inoculation, using a scale where O = no disease and 5 = maximum susceptibility. Five Xam strains were used: CIO-84, CIO-1, CIO-136, CIO-295, and ORST X-27. Area under the disease progress curve (AUDPC) was used as a quantitative measure of resistance in QTL analysis by single-marker regression. Based on the AUDPC values, eight QTLs (quantitative trait loci), located on linkage groups B, D, L, N, and X of the femalederived framework map, were found to explain 9-20% of the phenotypic variance of the crop's response to the five Xain strains. With the male-derived framework map, four QTLs on linkage groups G and C explained 10.7-27.1% of the variance. A scheme to confirm the usefulness of these markers in evaluating segregating populations for resistance to CBB is proposed.

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Differentiation of Rhodococcus species by ribotyping

Jorks

1996

J. Basic Microbiol.

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The ribosomal RNA gene restriction patterns (ribotyping) was investigated with respect to the characterization of Rhodococcus species and R. rhodochrous strains. Chromosomal DNA was prepared, digested with BamH I, blotted, and hybridized with acetylaminofluorene-labelled 16 + 23S rRNA from E. coli. The type strains of seven Rhodococcus species studied gave different hybridization patterns in each case. All strains tested were clearly distinguishable by ribotyping. Patterns contained two to eight bands between 1.4 kb and 11.8 kb and demonstrated the high genetic divergence of genus Rhodococcus. Investigation of nine R. rhodochrous strains resulted in patterns with seven or eight bands. One fragment, 4.4 kb in size, was common to all R. rhodochrous strains and appears to be characteristic of R. rhodochrous. Ribotyping was evaluated as a tool for distinguishing between Rhodococcus species.

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Assessment of genetic diversity among strains of Xanthomonas campestris pv. manihotis

Cited by 37 publications

References 22 publications

Genetic Structure and Population Dynamics of Xanthomonas axonopodis pv. manihotis in Colombia from 1995 to 1999

Genetic Structure and Population Dynamics of Xanthomonas axonopodis pv. manihotis in Colombia from 1995 to 1999

Genetic mapping of resistance to bacterial blight disease in cassava (Manihot esculenta Crantz)

Differentiation of Rhodococcus species by ribotyping

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