Broad-spectrum virus resistance in transgenic plants expressing pokeweed antiviral protein.

Abstract

Exogenous application of pokeweed antiviral protein (PAP), a ribosome-inhibiting protein found in the cell walls of Phytolacca americana (pokeweed), protects heterologous plants from viral infection. A cDNA clone for PAP was isolated and introduced into tobacco and potato plants by transformation with Agrobacterium tumefaciens. Transgenic plants that expressed either PAP or a double mutant derivative of PAP showed resistance to infection by different viruses. Resistance was effective against both mechanical and aphid transmission. Analysis of the vacuum infiltrate of leaves expressing PAP showed that it is enriched in the intercellular fluid. Analysis of resistance in transgenic plants suggests that PAP confers viral resistance by inhibiting an early event in infection. Previous methods for creating virus-resistant plants have been specific for a particular virus or closely related viruses. To protect plants against more than one virus, multiple genes must be introduced and expressed in a single transgenic lne. Expression of PAP in transgenic plants offers the possibility of developing resistance to a broad spectrum of plant viruses by expression of a single gene.

Expression of Pokeweed Antiviral Protein in Transgenic Plants Induces Virus Resistance in Grafted Wild-Type Plants Independently of Salicylic Acid Accumulation and Pathogenesis-Related Protein Synthesis

“…PAP also inhibits growth of tumor cells (Stirpe et al, 1992). Positive correlations were reported between RIP-catalyzed depurination of tobacco ribosomes and antiviral activity of exogenously applied RIPs (Taylor et al, 1994) and between the extent of inhibition of virus infection by PAP and the depurination of host ribosomes (Chen et al, 1992).We reported that transgenic tobacco and potato plants expressing PAP show broad-spectrum resistance to infection by different viruses (Lodge et al, 1993). In this paper we studied the mechanism of this resistance by grafting wild-type tobacco plants on transgenic tobacco plants expressing PAP.…”

“…We reported that transgenic tobacco and potato plants expressing PAP show broad-spectrum resistance to infection by different viruses (Lodge et al, 1993). In this paper we studied the mechanism of this resistance by grafting wild-type tobacco plants on transgenic tobacco plants expressing PAP.…”

“…In contrast, transgenic plants expressing an active-site mutant PAP are not able to induce resistance in grafted wild-type scions, demonstrating that enzymatic activity of PAP is required to induce the resistant state in systemic tissues. (Lodge et al, 1993). Grafts were prepared with 6-week-old scions and rootstocks as described by Vernooij et al (1994).…”

A systemic antiviral resistance‐inducing protein isolated from Clerodendrum inerme Gaertn. is a polynucleotide:adenosine glycosidase (ribosome‐inactivating protein)

“…The notion that RIPs may have a defensive role against viruses is supported by the resistance acquired by plants transfected with RIP genes [19][20][21] and, indirectly, by the expression of a RIP in tissues of sugar beet plants consequent to…”

Culture senescence and abscisic acid induce saporin production in cultured roots of Saponaria officinalis

“…However, despite results indicating that the exogenous application of RIPs to plants and the expression of transgenes confers both viral and fungal resistance (Logemann et al, 1992 ;Lodge et al, 1993), there is no compelling evidence that this is the physiological role of these proteins in vivo.…”