Transposons as tools for functional genomics

Transposons have been used extensively for insertional mutagenesis in sever al plant species. These include species where highly active endogenous syst ems are available such as maize and Antirrhinum majus, as well as species w here heterologous transposons have been introduced through transformation, such as Arabidopsis thaliana and tomato. Much of the past use of transposon s has been in traditional 'forward genetics' approaches, to isolate and mol ecularly characterize genes identified by mutant phenotypes. With the rapid progress in the genome projects of different plants, large-scale transposo n mutagenesis has become an important component of functional genomics, per mitting assignment of functions to sequenced genes through reverse genetics . Different strategies can be pursued, depending upon the properties of the transposon such as the mechanism and control of transposition, and those o f the host plant such as transformation efficiency. The successful use of t hese strategies in A. thaliana has made it possible to develop databases fo r reverse genetics, where screenings for the knockout of a gene of interest can be performed by computer searches. The extension of these technologies to other plants, particularly agronomically important crops such as rice, is now feasible. (C) 2001 Editions scientifiques et medicales Elsevier SAS.