RESUMO
Natural mutations in translation initiation factor eIF4E confer resistance to potyviruses in many plant species. Potato is a staple food crop plagued by several potyviruses, yet to date no known eIF4E-mediated resistance genes have been identified. In this study, we demonstrate that transgenic expression of the pvr1(2) gene from pepper confers resistance to Potato virus Y (PVY) in potato. We then use this information to convert the susceptible potato ortholog of this allele into a de novo allele for resistance to PVY using site-directed mutagenesis. Potato plants overexpressing the mutated potato allele are resistant to virus infection. Resistant lines expressed high levels of eIF4E mRNA and protein. The resistant plants showed growth similar to untransformed controls and produced phenotypically similar tubers. This technique disrupts a key step in the viral infection process and may potentially be used to engineer virus resistance in a number of economically important plant-viral pathosystems. Furthermore, the general public may be more amenable to the 'intragenic' nature of this approach because the transferred coding region is modified from a gene in the target crop rather than from a distant species.
Assuntos
Resistência à Doença , Fator de Iniciação 4E em Eucariotos/genética , Engenharia Genética , Doenças das Plantas/prevenção & controle , Potyvirus/patogenicidade , Solanum tuberosum/genética , Alelos , Sequência de Aminoácidos , Capsicum/genética , Capsicum/imunologia , Fator de Iniciação 4E em Eucariotos/imunologia , Regulação da Expressão Gênica de Plantas , Genes de Plantas , Dados de Sequência Molecular , Mutagênese Sítio-Dirigida , Doenças das Plantas/imunologia , Doenças das Plantas/virologia , Plantas Geneticamente Modificadas/genética , Plantas Geneticamente Modificadas/imunologia , Plantas Geneticamente Modificadas/virologia , Potyvirus/genética , Alinhamento de Sequência , Solanum tuberosum/imunologia , Solanum tuberosum/virologia , Transformação GenéticaRESUMO
Despite long-standing plant breeding investments and early successes in genetic engineering, plant viral pathogens still cause major losses in agriculture worldwide.Early transgenic approaches involved the expression of pathogen-derived sequences that provided limited protection against relatively narrow ranges of viral pathotypes. In contrast,this study demonstrates that the ectopic expression of pvr1, a recessive gene from Capsicum chinense, results in dominant broad-spectrum potyvirus resistance in transgenic tomato plants (Solanum lycopersicum). The pvr1 locus in pepper encodes the eukaryotic translation initiation factor eIF4E. Naturally occurring point mutations at this locus result in monogenic recessive broad-spectrum potyvirus resistance that has been globally deployed via plant breeding programmes for more than 50 years. Transgenic tomato progenies that over-expressed the Capsicum pvr1 allele showed dominant resistance to several tobacco etch virus strains and other potyviruses, including pepper mottle virus, a range of protection similar to that observed in pepper homozygous for the pvr1 allele.