Author: Georgina Marie DonovanPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Characterisation of Pathotypes of Bean Common Mosaic Virus (BCMV)
Author: Georgina Marie DonovanMolecular Characterization and Detection of Two Common Bean (Phaseolus Vulgaris L.) Pathogens
Author: Pablo GuzmanDetermining the Mechanism of the Recessive Resistance to Bean Common Mosaic Virus (BCMV) Conferred by the Bc-1 and Bc-2 Recessive Genes in Common Bean, and Biological and Molecular Characterization of a New Strain of BCMV
Author: Gardenia Edith Orellana ArreagaPublisher:
ISBN: 9781085597043
Category : Bean common mosaic virus
Languages : en
Pages : 106
Book Description
Bean common mosaic virus (BCMV) is an important pathogen affecting common bean and other legumes. BCMV is an aphid-transmitted virus, which can also be seed-transmissible in common bean with efficiencies of up to 80%, depending on virus strain and bean cultivar. The virus belongs to the genus Potyvirus (family Potyviridae), having an approximately 10-kb single-stranded, positive-sense RNA genome. BCMV resistance in common bean is governed by one dominant (I) gene and four recessive (bc-u, bc-1, bc-2, and bc-3) genes which are deployed by breeders in different combinations to protect commercial bean cultivars against the virus. The dominant I gene confers extreme resistance or immunity against all strains of BCMV when the temperature stays below 30°C, and variable types of local and systemic necrosis when temperature exceeds 30°C. The bc-3 gene was identified as an eIF4E translation initiation factor gene mediating resistance through disruption of the interaction between this protein and the VPg protein of the virus. The mode of action of bc-1 and bc-2 in expression of BCMV resistance was unknown until this work. To investigate the possible role of both bc-1 and bc-2 genes in replication, cell-to-cell, and long distance movement of BCMV in P. vulgaris, we tested virus spread of eight BCMV isolates representing pathogroups I, IV, VI, VII, and VIII, in a set of bean differentials expressing different combinations of six resistance alleles including bc-u, bc-1, bc-12, bc-2, bc-22, and bc-3. The data suggest that bc-1 and bc-2 recessive resistance genes have no effect on the replication and cell-to-cell movement of BCMV, but affect systemic spread of BCMV in common bean. The BCMV resistance conferred by bc-1 and bc-2 and affecting systemic spread was found only partially effective when these two genes were expressed singly. The efficiency of the restriction of the systemic spread of the virus was greatly enhanced when the alleles of bc-1 and bc-2 genes were combined together.Beside common bean, there are other crop legumes that are susceptible to BCMV, such as peanut, soybean, and azuki bean. In this thesis, I described a new strain of BCMV from lima bean with distinct biological and molecular characteristics found in Honolulu, HI. This new BCMV strain, BCMV-A1, was able to partially overcome resistance to the virus conferred by bc-1 and bc-2 alleles in common bean, establishing an asymptomatic systemic infection in some common bean cultivars. Later, two BCMV isolates were found in commercial common bean samples in Idaho exhibiting 99% identity to BCMV-A1 in partial genome sequence. This new BCMV strain from lima bean, BCMV-A1, may present a threat for the common bean production.
Mémoire à l'eminentissime et Sérénissime College Electoral
Author: Multiplication and Distribution of Bean Common Mosaic Virus (BCMV) in Bean
Author: Ephraim J. A. EkpoPublisher:
ISBN:
Category : Bean common mosaic virus
Languages : en
Pages : 148
Book Description
Relationships Between Pathotypes of Bean Common Mosaic Virus
Author: Austin Walter MillarIdentification of Necrosis-inducing Strains of Bean Common Mosaic Virus and Breeding for Resistance
Author: Milton A. Morales LopezPublisher:
ISBN:
Category : Bean common mosaic virus
Languages : en
Pages : 186
Book Description
Mechanism of Resistance to Bean Common Mosaic Virus Conferred by the I Locus in Phaseolus Vulgaris L.
Author: Molly Melinda Cadle-DavidsonPublisher:
ISBN:
Category :
Languages : en
Pages : 228
Book Description
Gene Ecology of the Climbing Common Bean (Phaseolus Vulgaris) - Bean Common Mosaic Virus/ Bean Common Mosaic Necrosis Virus (BCMV/BCMVN) Relationship in Rwanda
Author: Alice KabejaPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Common beans (Phaseolus vulgaris) are nutritionally, culturally, and economically an important legume crop in Rwanda. Beans provide 32 and 65 percent of calories and protein intake in the Rwandan diet, whereas protein sourced from animal provides only 4 percent of the protein intake. Unfortunately, common bean production is constrained by multiple biotic and abiotic factors in this country. Among others, Bean common mosaic virus and Bean common mosaic necrosis virus (BCMV/BCMNV) are seedborne viral pathogens that are the main constraint in common bean production. The only effective control of these pathogens is through the use of genetic resistance. Currently, the status of BCMV/BCMNV in Rwanda is not known. To contribute to the research in breeding common bean against BCMV/BCMNV in Rwanda, I sought to better understand the variability and biology of the BCMV/BCMNV pathogen to assist in developing a resistance strategy in common bean that is broader and stronger. In the first chapter, I was interested in determining the types of BCMV/BCMNV strains that are present in Rwanda. I was also interested in identifying the selective pressures these viruses are subjected to and how they govern the evolution of these viruses in Rwanda. Furthermore, I wanted to find out if there are alternate hosts other than common bean for BCMV/BCMNV in Rwanda. To gain this information, I surveyed common bean fields extensively in high-altitude areas of Rwanda. The biological and molecular pathogenic characterization studies of isolates of BCMV and BCMNV resulting from these surveys revealed the exclusive presence of BCMNV in Rwanda. No BCMV strain were found. We observed the predominance of the NL-3 strain of BCMNV. The study of genetic diversity for coat protein (CP) fragment of the BCMNV isolates showed a low genetic diversity ([pi] = 0.015623). The mean [omega] (dN/dS) value for CP of 27 isolates analyzed here was less than 1.0, indicating that the CP segment of BCMNV in Rwanda is subject to negative or purifying selection. No alternative hosts to Phaseolus vulgaris for either BCMV or BCMNV were identified in this study. For now, the resistance of BCMV/BCMNV in host plant is controlled by seven resistance genes: one dominant gene (I gene), five recessive strain-specific genes (bc-1, bc-12, bc-2, bc-22, and bc-3), and one strain-nonspecific epistatic gene (bc-u). However, few studies have been carried out on bc-12 (Miklas et al.; 2000). In the second chapter, through the development and evaluation of Recombinant Inbreed Lines (RIL) under greenhouse conditions, we investigated if any minor, quantitative loci could be identified for resistance to BCMNV, which would have originated in either of the parents, RWV3006 (bc-12) or Mshindi (bc-12), and would complement the major resistance gene bc-12. A quantitative trait loci (QTL) study done on these RILs confirmed the presence of bc-12 gene (SS715647636 QTL) on chromosome PV03 as expected. However, another QTL (SS715645701) with a smaller effect was found on Pv09. Interestingly, the positive (resistant) allele at this QTL came from RWV 3006, the susceptible parent. Results from this study showed that the combination of both QTLs increases resistance, either at the heterozygous or homozygous state. It sets the stage for further surveys of minor viral resistance genes in common-bean germplasm. To facilitate future breeding efforts, in the third chapter I attempted to obtain tightly-linked markers useful for marker-assisted selection (MAS) of the bc-12 gene in the presence of other epistatic virus resistance genes. These markers should be more broadly applicable to different genetic backgrounds, reproducible across laboratories, and able to distinguish homozygotes from heterozygotes (co-dominant). Based on a known SNP marker linked to bc-12 resistance gene, we developed a dCAPS (derived Cleaved Amplified Polymorphic Sequence) marker. However, it was not possible to clearly visualize the polymorphism generated by the designed dCAPSHindIII marker on agarose gels in all tested genotypes. This may be explained by the small size of the marker. The low resolution of the agarose gel could not detect small size differences as effectively as polyacrylamide gel electrophoresis, which can distinguish fragments with few (one to five) base pairs difference. We suggest that the marker should be tested in a larger number of different bean seed types to ascertain its usefulness in different bean classes. Furthermore, in future work with this dCAPSHindIII marker, the use of polyacrylamide gel could facilitate effective discrimination between DNA fragments from the resistant and susceptible parents.
Factors Affecting the Production of Local Lesions by Bean Common Mosaic Virus (BCMV)
Author: Gustavo Enrique TrujilloPublisher:
ISBN:
Category : Beans
Languages : en
Pages : 184
Book Description