|Naderpour, Masoud -|
|Lund, Ole Søgaard -|
|Johansen, Elizabeth -|
Submitted to: Molecular Plant Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 28, 2009
Publication Date: March 1, 2010
Citation: Naderpour, M., Lund, O., Larsen, R.C., Johansen, E. 2010. Potyviral resistance derived from cultivars of Phaseolus vulgaris carrying bc-3 is associated with the homozygotic presence of a mutated eIF4E allele. Molecular Plant Pathology. 255-263. Interpretive Summary: Eukaryotic translation initiation factors (eIFs) play a central role in infection in plants by a large group of plant viruses called potyviruses. When mutations of one of these initiation factors, eIF4E, occurs in plants such as common bean where a recessive resistance is developed against the viruses. Four specific recessive genes have been proposed to control resistance to strains of the the potyviruses Bean common mosaic virus (BCMV) and Bean common mosaic necrosis virus. We were able to demonstrate that bean genotypes reported to carry the bc-3 resistance gene carried four unique mutations within the eIF4E initiation factor. This set of mutations closely resembled a pattern of eIF4E mutations determining potyvirus resistance in other plant species. Thus, a mutated eIF4E appears to be associated with a major component of potyvirus resistance present in beans posessing the bc-3 gene, and may also be associated with resistance to Clover yellow vein virus, another important potyvirus infecting snap bean crops.
Technical Abstract: Eukaryotic translation initiation factors (eIFs) play a central role in potyviral infection. Accordingly, mutations in the gene encoding eIF4E have been identified as a source of recessive resistance in several plant species. In common bean, Phaseolus vulgaris, four recessive genes, bc-1, bc-2, bc-3 and bc-u, have been proposed to control resistance to the potyviruses Bean common mosaic virus (BCMV) and Bean common mosaic necrosis virus. In order to identify molecular entities for these genes, we cloned and sequenced P. vulgaris homologues of genes encoding the eIF proteins eIF4E, eIF(iso)4E and nCBP. Bean genotypes reported to carry bc-3 resistance were found specifically to carry nonsilent mutations at codons 53, 65, 76 and 111 in eIF4E. This set of mutations closely resembled a pattern of eIF4E mutations determining potyvirus resistance in other plant species. The segregation of BCMV resistance and eIF4E genotype was subsequently analysed in an F2 population derived from the P. vulgaris all-susceptible genotype and a genotype carrying bc-3. F2 plants homozygous for the eIF4E mutant allele were found to display at least the same level of resistance to BCMV as the parental resistant genotype. At 6 weeks after inoculation, all F2 plants found to be BCMV negative by enzyme-linked immunosorbent assay were found to be homozygous for the mutant eIF4E allele. In F3 plants homozygous for the mutated allele, virus resistance was subsequently found to be stably maintained. In conclusion, allelic eIF4E appears to be associated with a major component of potyvirus resistance present in bc-3 genotypes of bean.