T-DNA Tagging in a Genomics Era

Abstract

Referee: Dr. Tatsuo Kakimoto, Department of Biology, Graduate School of Science, Osaka University, Machiikaneyama 1-1, Toyonaka, Osaka 560-0043 JapanFrom a relatively simple start, T-DNA tagging has emerged to become an important tool in plant physiology and molecular biology. Initially, it was primarily used as a means of gene isolation. A T-DNA insertion might result in an obvious, changed phenotype in the host plant and the sequence of the tag provided a landmark allowing its isolation along with the mutated gene. However, more recently, with plant genome sequences becoming available along with transgenic plant populations where collectively T-DNA insertions may saturate the genome, T-DNA insertion is being used increasingly to determine gene function. A variety of T-DNA gene tags are available. Many integrate within transcriptional units so that promoters, enhancers, exons, and introns can be tagged. In such cases if the tag contains marker genes endogenous patterns of expression of tagged sequences can be monitored. Tags containing transcriptional enhancers can be used to create gain of function mutations by the activation of gene expression. In the foreseeable future we can anticipate that with the model plant Arabidopsis libraries will become available where accessions will represent the knockout and/or activation of every gene coding region as defined by sequencing. Increasingly, T-DNA tagging is also being used to characterize genes in other plant species. Thus, it may be anticipated that this method of gene tagging will play an important role in investigating gene function in plant developmental processes that are not easily accessible with Arabidopsis.