Pathways to Plant Genetic Manipulation Employing Agrobacterium

Abstract

The adaption of the Agrobacterium tumefaciens Ti plasmid as a vector for plant transformation is an enabling technology permitting plant molecular biologists to rapidly expand the frontiers of knowledge about the fundamental biological processes of gene function, expression and regulation (See Fraley et al., 1986 for a recent review). The ability to introduce native or modified genes into plants has moved plant molecular biology from a descriptive mode to a manipulative mode where the effects of specific alterations in gene sequences can be assayed. In the four short years since the first reports of the successful use of the system for the introduction and expression of a foreign gene in plant tissues, researchers have identified specific nucleotide sequences responsible for light regulated expression of certain genes (Broglie et al., 1984; Herrera-Estrella et al., 1984; Morelli et al., 1985). Other groups (Nagy et al., 1985; Beachy et al., 1985; Sengupta-Gopalan et al., 1985) have shown that newly introduced genes exhibit the characteristic tissue specific and/or developmental stage specific expression that they displayed in the plants from which they were isolated. Still others (Schreier et al., 1985) have begun to identify the portions of transit peptides responsible for proper compartmentalization of proteins within a plant cell. The Ti transformation system has become a tool for the study of virus host range, symptom production and replication (Grimsley et al., 1986, Rogers et al., 1986 b; Grimsley and Bisaro, this volume) as well as cellular recombination processes.