Insertional and Transposon Mutagenesis

Various forms of mutagenesis are being developed into an increasingly sophisticated range of tools for functional genomics, providing the means to generate genome-wide libraries of mutants that allow the interrupted genes to be identified rapidly. In combination with other genomic resources, such as genome sequences and expressed sequence tag (EST) collections, this provides an efficient route to high-throughput functional annotation of genomes. While basic insertion constructs generate loss-of-function phenotypes, additional refinements show how the interrupted genes are expressed and may even produce gain-of-function phenotypes resulting from overexpression and ectopic expression. The use of such transposon or T-DNA libraries in concert with DNA arrays, expression proteomics, protein structural analysis, and protein interaction mapping provides an unprecedented integrated approach to the functional analysis of plants. More recently several genome editing technologies have become available for the creation of useful mutations and/or gene replacements in plants. Probably the most powerful of these methods is the CRISPR (clustered, regularly interspaced, short palindromic repeats) system that was first used to modify crop genomes in 2013. These genome editing technologies have the potential, not only to facilitate the repair or deletion of unsuitable genes but also to facilitate the transfer of entire metabolic pathways into a plant, as discussed in the case of alkaloids in article PLANT BREEDING AND GENETICS | Alkaloids.