ABSTRACT
Historically, the study of plant viruses has contributed greatly to the elucidation of eukaryotic biology. Recently, concurrent with the development of viruses into expression vectors, the biotechnology industry has developed an increasing number of disease therapies utilizing recombinant proteins. Plant virus vectors are viewed as a viable option for recombinant protein production. Employing pathogens in the process of creating added value to agriculture is, in effect, making an ally from an enemy. This review discusses the development and use of viruses as expression vectors, with special emphasis on (+) strand RNA virus systems. Further, the use of virus expression vectors in large-scale agricultural settings to produce recombinant proteins is described, and the technical challenges that need to be addressed by agriculturists and molecular virologists to fully realize the potential of this latest evolution of plant science are outlined.
Subject(s)
Agriculture/methods , Plant Viruses/metabolism , Plants/virology , Comovirus/genetics , Comovirus/metabolism , Gene Expression Regulation, Plant , Gene Expression Regulation, Viral , Genetic Vectors/genetics , Plant Viruses/genetics , Plants/genetics , Plum Pox Virus/genetics , Plum Pox Virus/metabolism , Potexvirus/genetics , Potexvirus/metabolism , RNA Viruses/genetics , RNA Viruses/metabolism , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Tobacco Mosaic Virus/genetics , Tobacco Mosaic Virus/metabolism , Tombusvirus/genetics , Tombusvirus/metabolism , VaccinesABSTRACT
Knowledge of gene function is critical to the development of new plant traits for improved agricultural and industrial applications. Viral expression vectors offer a rapid and proven method to provide epigenetic expression of foreign sequences throughout infected plants. Expression of these sequences from viral vectors can lead to gain- or loss-of-function phenotypes, allowing gene function to be determined by phenotypic or biochemical effects in the infected plant. Tobacco mosaic virus and barley stripe mosaic virus expression vectors have been developed to express foreign gene sequences in dicotyledonous and monocotyledonous hosts, respectively. Large-scale application of both viral vector systems for gene function discovery in Nicotiana and barley hosts resulted in high infection rates and produced distinctive visual phenotypes in approximately 5% of transfected plants. Novel genes expressing potential herbicide target proteins in addition to genes promoting stem elongation, leaf development and apical dominance were identified in the large-scale screening. This report illustrates the adaptability of viral vectors for gene function discovery in higher plants.
