THE USE OF NATURAL VARIATION IN ARABIDOPSIS FOR FUNCTIONAL ANALYSIS

¹ Laboratory of Genetics, Wageningen University, Arboretumlaan 4, 6703 BD, Wageningen , Netherlands

² Laboratory of Plant Physiology, Wageningen University, Arboretumlaan 4, 6703 BD, Wageningen , Netherlands

³ Centro Nacional de Biotecnologia, Campus Universidad Autonoma, Cantoblanco, 28049, Madrid, Spain

The functional analysis of Arabidopsis genes has been largely based on the phenotypic characterisation of mutants selected by forward and reverse genetics in a very limited number of laboratory ’wild-type’ genotypes. As an alternative to induced mutants, an important source of genetic variation can be found among naturally occurring populations of Arabidopsis called. Considerable variation has been found for potentially adaptive traits such as resistance (measured as plant survival or damage) to biotic and abiotic stresses, physiological developmental and biochemical traits. The study of natural variation requires quantitative trait loci (QTL) analysis. For efficient QTL analysis sets of recombinant inbred lines have been developed, which show segregation for a large number of traits including those important in crop plants. The variation and genetic analysis of traits such as sugar, starch, phytate and mineral accumulation, plant growth, enzyme activities, seed dormancy and seed quality has been analysed. The feasibility to clone individual QTL by a combination of map based cloning, using near isogenic introgression lines has been demonstrated by the isolation of a gene conferring daylength insensitivity, which appears to encode a cryptochrome 2 protein with increases protein stability. In case of seed dormancy the combination of fine mapping of a single QTL and a mutant approaches allowed the isolation of gene controlling seed dormancy. QTL variation for enzyme activities often co-locates with structural genes but also potential regulatory loci have been found.