RESUMO
Transgenic potato plants, cultivar Désirée, were produced that contained the coat protein gene of potato leafroll luteovirus (PLRV). The transformed potato plants expressed the PLRV coat protein (CP) RNA sequences but accumulation of coat protein in transgenic tissues could not be detected. Upon inoculation with PLRV, the PLRV CP RNA expressing potato plants showed a reduced rate of virus multiplication.
Assuntos
Capsídeo/genética , Doenças das Plantas , Vírus de Plantas/fisiologia , Solanum tuberosum/genética , Sequência de Bases , Northern Blotting , Southern Blotting , Capsídeo/biossíntese , Clonagem Molecular , DNA Viral , Ensaio de Imunoadsorção Enzimática , Vetores Genéticos , Dados de Sequência Molecular , RNA Viral/biossíntese , RNA Viral/genética , Solanum tuberosum/microbiologia , Transformação Genética , Replicação ViralRESUMO
Plant viral genomes are relatively small and in the past decade many have been characterized at the molecular level. This has prompted research into the development of virus resistance based on interference with the viral multiplication cycle by teh introduction of viral sequences into the plant genome. Several strategies have been tested. The most successful one so far involves the constitutive expression of the coat protein gene of the virus against which resistance is desired. In this review we describe progress made in engineering virus resistance into potato, an important agricultural crop. To this end the molecular structure of the potato viruses X and Y and leafroll is discussed as well as the introduction of resistance against potato virus X into potato. In addition, we address the question of preservation of cultivar-specific characteristics, an important prerequisite for commercial application. Finally, recent investigations for alternative forms of virus resistance are described against the background of the results of coat protein-mediated protection.
Assuntos
Vírus de Plantas/genética , Plantas/microbiologia , Capsídeo/genética , Engenharia Genética , Plantas/genética , RNA/genética , RNA Antissenso/genética , RNA Satélite , RNA Viral/genética , Solanum tuberosum/genética , Solanum tuberosum/microbiologia , Interferência Viral/genéticaRESUMO
Double-stranded cDNA of potato virus X (PVX) genomic RNA has been cloned and sequenced. The sequence [6435 nucleotides excluding the poly(A) tract] revealed five open reading frames (ORFs) which were numbered one to five starting at the 5' terminus of the RNA. They encoded proteins of Mr 165588 (166K), 24622 (25K), 12324 (12K), 7595 (8K) and 25080 (coat protein), respectively. ORFs 1 and 2 were inphase coding regions. The ORF 1 product contained domains of homology with the tobacco mosaic virus 126K and 183K products. The ORF 2 and 3 products showed homologies with the barley stripe mosaic virus 58K and 14K proteins, the beet necrotic yellow vein virus 42K and 13K products and the white clover mosaic virus 26K and 13K products, respectively. The significance of these homologies with respect to putative functions of the PVX-encoded proteins are discussed.