ABSTRACT
An important aim of plant biology is to understand how genes regulate growth, development and metabolism. A number of techniques have been developed that allow gene cloning, for further analysis of molecu-ular mechanisms. One powerful approach has involved the screening of mutagenized populations, to identify genes that, when mutated, result in a pheno-typic aberration. It is becoming increasingly apparent that a large number, perhaps the majority, of genes in plants and other organisms are genetically redundant, though nevertheless functional, and these may be inaccessible by conventional mutant screens. Two alternative genetic approaches to gene identification are entrapment and activation tagging, in which either transgenes are activated by regulatory sequences associated with native genes (entrapment tagging), or transgenes are used to drive the overexpression of native genes (activation tagging). Since both methods can generate dominant phenotypes as well as gene knockout by insertion mutagenesis, they represent valuable additions to the genetic tools available to study gene regulation in plants.
