Stephen Gary Rogers

Use of cointegrating Ti plasmid vectors

The domestication of the crown gall disease causing Agrobacterium tumefaciens Ti plasmid for use in stable introduction of DNAs into the genome of plants has produced a technology permitting unparalleled experimental and practical manipulation of the genetic constitution of plants. Modified Ti plasmids carrying native or modified plant genes have permitted detailed analysis of the sequences necessary for light [5, 11, 12] and tissue or developmental [13, 4, 16] regulation of plant gene expression. Protein sequences important for the internalization of proteins within plastids have been elucidated [17]. The Ti transformation system has become a tool for the study of virus host range, symptom production and replication [10, 15]. Recently, the Ti system has been used to introduce the maize Ac transposable element into tobacco to examine the process and regulation of transposition and for use as a potential gene tagging system [3].

Current Vectors for Plant Transformation

Publisher Summary One of the most significant recent advances in the area of plant molecular biology has been the development of the Agrobacterium tumefaciens Ti plasmid as a vector system for the transformation of plants. Ti plasmid transformation vectors provide a facile means to introduce homologous and heterologous DNAs and genes into plants. This ability to transfer genetic information between plants and other organisms permits investigators to study the temporal and tissue-specific expression of genes as well as the stability of the gene products. With this tool, the promoter regions responsible for light-regulated expression of certain genes and the portions of transit peptides responsible for proper compartmentalization of proteins within the plant cell are being elucidated. This chapter discusses the correct tissue-specific and developmentally regulated expression of several reintroduced genes. The Ti transformation system has also been adapted for the study of virus host range, symptom production, and replication, as well as host cell recombination processes. For crop improvement uses, the Ti transformation system has been used to obtain plants that are resistant to the nonselective herbicide Roundup®, which express the Bacillus thuringiensis crystal toxin and are resistant to tobacco hornworm and that produce the tobacco mosaic virus coat protein and are resistant to superinfection by virulent strains of this virus.