AFLP assessment of genetic variability in cassava accessions (Manihot esculenta) resistant and susceptible to the cassava bacterial blight (CBB)

Genome ◽  
1999 ◽  
Vol 42 (2) ◽  
pp. 163-172 ◽  
Author(s):  
Gilda Sanchez ◽  
Silvia Restrepo ◽  
Myriam-Cristina Duque ◽  
Martin Fregene ◽  
Merideth Bonierbale ◽  
...  
Keyword(s):  
Genetic Variability ◽  
Manihot Esculenta ◽  
Bacterial Blight ◽  
Cassava Bacterial Blight

AFLP assessment of genetic variability in cassava accessions (Manihot esculenta) resistant and susceptible to the cassava bacterial blight (CBB)

Genome ◽  
1999 ◽  
Vol 42 (2) ◽  
pp. 163-172 ◽  
Author(s):  
Gilda Sanchez ◽  
Silvia Restrepo ◽  
Myriam-Cristina Duque ◽  
Martin Fregene ◽  
Merideth Bonierbale ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Manihot Esculenta ◽  
Bacterial Blight ◽  
Multiple Correspondence Analysis ◽  
Aflp Analysis ◽  
Resistance Screening ◽  
Base Resistance ◽  
Cassava Bacterial Blight ◽  
Xanthomonas Axonopodis ◽  
Cassava Varieties

Cassava bacterial blight (CBB) is caused by Xanthomonas axonopodis pv. manihotis (Xam). Resistance is found in Manihot esculenta and, in addition, has been introgressed from a wild relative, M. glaziovii. The resistance is thought to be polygenic and additively inherited. Ninety-three varieties of M. esculenta (Crantz) were assessed by AFLPs for genetic diversity and for resistance to CBB. AFLP analysis was performed using two primer combinations and a 79.2% level of polymorphism was found. The phenogram obtained showed between 74% and 96% genetic similarity among all cassava accessions analysed. The analysis permitted the unique identification of each individual. Two Xam strains were used for resistance screening. Variation in the reaction of cassava varieties to Xam strains was observed for all plant accessions. The correlation of resistance to both strains, had a coefficient of 0.53, suggesting the independence of resistance to each strain. Multiple correspondence analysis showed a random distribution of the resistance/susceptibility response with respect to overall genetic diversity as measured by AFLP analysis. A total heterozygosity index was calculated to determine the diversity within clusters as well as among them. Our results demonstrate that resistance to CBB is broadly distributed in cassava germplasm and that AFLP analysis is an effective and efficient means of providing quantitative estimates of genetic similarities among cassava accessions.Key words: amplified fragment length polymorphism, genetic base, resistance screening, Xanthomonas axonopodis pv. manihotis.

Xanthomonas manihotis. [Descriptions of Fungi and Bacteria].

1977 ◽  
Author(s):  
J. F. Bradbury
Keyword(s):  
Geographical Distribution ◽  
Manihot Esculenta ◽  
Bacterial Blight ◽  
Vascular Tissue ◽  
Cassava Bacterial Blight ◽  
Progressive Die ◽  
Leaf Spots ◽  
Planting Material ◽  
Rain Splash ◽  
Infected Material

Abstract A description is provided for Xanthomonas manihotis. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: On Manihot esculenta. DISEASE: Cassava bacterial blight. The symptoms are unusually diverse, and include spotting, blight and wilt of leaves, wilt and dieback of stems, necrosis of vascular tissue of stems and roots, and exudation of bacterial ooze. The disease may begin with water-soaked angular leaf spots that enlarge and coalesce, forming necrotic areas and eventually causing the leaf to dry and fall. In moist conditions ooze is formed on the lesions. Infection may travel back to the petioles and stems, young stems being particularly susceptible. A progressive die-back may follow. The roots usually remain healthy in appearance, but in some susceptible varieties dry, rotted spots may develop around necrosed vascular strands (Lozano, 1975). When infected material is planted the first symptoms are wilting and dieback of the young shoots soon after emergence. GEOGRAPHICAL DISTRIBUTION: Argentina, Brazil, Colombia, Venezuela, Nicaragua, Nigeria, Ghana, Togo, Cameroon, Zaire, Uganda, Malawi, Madagascar, Mauritius, India, Malaysia, Indonesia, Taiwan. CMI Map 521, ed. 1, 1977. TRANSMISSION: The disease is spread in the field mainly by rain-splash. Dissemination is, therefore, mainly downwind (53, 3724). Insects may also transmit the disease, as does Pseudotheraptus devastans in Zaire (Maraite & Meyer, 1975). The disease overwinters and travels from one area to another in infected planting material. Infested tools may also spread disease, especially as harvesting is accompanied by much cutting (Lozano, 1975).

scholarly journals QTL identification for cassava bacterial blight resistance under natural infection conditions

2017 ◽  
Vol 22 (1) ◽  
pp. 19 ◽  
Author(s):  
Carolina Soto Sedano ◽  
Rubén Eduardo Mora Moreno ◽  
Fernando Calle ◽  
Camilo Ernesto López Carrascal
Keyword(s):  
Manihot Esculenta ◽  
Bacterial Blight ◽  
Natural Infection ◽  
Blight Resistance ◽  
Bacterial Blight Resistance ◽  
Manihot Esculenta Crantz ◽  
Cassava Bacterial Blight ◽  
Xanthomonas Axonopodis ◽  
Qtl Identification

La yuca, Manihot esculenta Crantz, representa la principal fuente de alimento para cerca de 1000 millones de personas. La producción de yuca se ve afectada por diversas enfermedades, una de las más serias es la bacteriosis vascular (CBB) causada por Xanthomonas axonopodis pv. manihotis (Xam). En este estudio se realizó un análisis de loci de rasgos cuantitativos (QTL) para la resistencia a CBB en condiciones naturales de infección, usando una población de mapeo constituida por 99 genotipos de hermanos completos segregantes y un mapa genético altamente denso basado en SNPs. La evaluación fenotípica se llevó a cabo en Puerto López (Meta), Colombia, durante la época de lluvias durante el segundo semestre de 2015. En la población de mapeo fueron detectados individuos con una segregación transgresiva tanto resistentes como susceptibles. A través de un análisis no paramétrico de intervalo simple, se detectaron dos QTL que explican el 10,9 y el 12,6 % de la varianza fenotípica de la resistencia en campo a CBB. Mediante análisis bioinformáticos se identificaron cuatro genes candidatos presentes en los intervalos de los QTL. Este trabajo representa un esfuerzo por dilucidar los mecanismos moleculares implicados en la resistencia de yuca a CBB.

scholarly journals Prevalence and Distribution of Cassava Bacterial Blight in the Kenyan Coast

2021 ◽  
Vol 3 (1) ◽  
pp. p7
Author(s):  
ANTONY Livoi ◽  
A. W. Mwang' ombe ◽  
E. Nyaboga ◽  
D. Kilalo ◽  
E. Obutho
Keyword(s):  
Manihot Esculenta ◽  
Bacterial Blight ◽  
Coastal Region ◽  
Management Program ◽  
Manihot Esculenta Crantz ◽  
Cassava Bacterial Blight ◽  
Xanthomonas Axonopodis ◽  
Major Constraint ◽  
Kenyan Coast ◽  
Cassava Production

Cassava (Manihot esculenta Crantz) is one of the staple food crops grown in Kenya. Diseases remain one of the major constraints for cassava production. Apart from other major viral diseaes Cassava mosaic and Cassava brown streak, Cassava bacterial blight (CBB) caused by Xanthomonas axonopodis pv manihotis and Xanthomonas axonopodis pv cassavae are a major constraint in cassava production in Kenya. This study was done to identify the prevalence, distribution, and farmers' knowledge of cassava bacterial blight in the coastal region of Kenya. A survey was conducted involving 250 farmers who were randomly selected from two regions of Kilifi and Taita Taveta counties. Among the 250 farmers interviewed, 61.6 % identified cassava bacterial blight symptoms in their farms. The main varieties found growing in the region were Tajirika, Karembo, Kibandameno, and Shibe which were all confirmed by farmers as susceptible to cassava bacterial blight. During the survey, plant samples were randomly collected in the field. Out of the 70 samples collected, 40 of them were confirmed positive with X.pv manihotis and X.pv cassavae which cause cassava bacterial blight. The study concluded that there is a widespread of cassava bacterial blight in Kilifi and Taita taveta counties. Kilifi County had the highest incidence of 22% with Taita Taveta having the lowest incidence of 13%. Kilifi County had a higher severity of 8% as compared to Taita Taveta which had 5% Severity. Therefore there is a need for a proper management program to be deployed in managing the disease to enhance cassava production in the region.

scholarly journals Cloning of a peroxidase gene from cassava with potential as a molecular marker for resistance to bacterial blight

2003 ◽  
Vol 46 (2) ◽  
pp. 149-154 ◽  
Author(s):  
Luiz Filipe Pereira ◽  
Paul H. Goodwin ◽  
Larry Erickson
Keyword(s):  
Manihot Esculenta ◽  
Bacterial Blight ◽  
Geographic Origin ◽  
Genomic Clone ◽  
Manihot Esculenta Crantz ◽  
Cassava Bacterial Blight ◽  
Bacterial Diseases ◽  
Peroxidase Gene ◽  
Glycosylation Sites ◽  
Large Intron

Cassava bacterial blight (CBB), caused by Xanthomonas axonopodis pv. manihotis, is considered one of the most important bacterial diseases of cassava (Manihot esculenta Crantz). In order to characterize the cassava genes involved in resistance to this disease, a genomic clone of a cationic peroxidase gene, MEPX1, was isolated by PCR from cassava cultivar MCOL 22. The DNA sequence of MEPX1 showed high homology with other plant peroxidase genes and contained a large intron typical of peroxidase genes. The predicted translation product showed a heme-ligand motif, also a characteristic of peroxidases, as well as phosphorylation, myristoylation and glycosylation sites. The amino acid sequence had 75 % homology with two Arabidopsis thaliana peroxidases. A Southern blot of 17 cassava cultivars, probed with MEPX1, showed multiple hybridization bands. Polymorphisms between cultivars generally reflected geographic origin, but there was also an association with resistance to CBB, indicating that MEPX1 could be a potentially useful marker for this trait.

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