ABSTRACT
Traditional genetic screens have mostly relied on the existence of null, or constitutively active variants of genes, usually obtained through chemical or insertional mutagenesis and the production of transgenic plants. This has allowed the function of an impressive number of genes to be assigned in model plants such as Arabidopsis thaliana. Genotyping is where quantitative genetics has made most progress in the last decade, allowing real genome-wide scans for quantitative trait loci (QTL) and precise targeted fine-mapping. Quantitative traits of interest can be very integrative, or closer to a specific function. Mapping a QTL relies on the existence of a genetic linkage between this locus and some of the molecular markers placed on the genetic map. The small size of A. thaliana plants and seedlings can be considered as an advantage for the geneticist, in that it allows the growth of thousands of plants under carefully controlled environmental conditions and/or to compare many genotypes in different environments.
