Arabidopsis thaliana is a first class model organism and the single most important species for fundamental research in plant molecular genetics.
A. thaliana was the first plant for which a high-quality reference genome sequence was determined (see below), and a worldwide research community has developed many other genetic resources and tools. The experimental advantages of A. thaliana have enabled many important discoveries. These advantages have been extensively reviewed, as has its role in fundamental discoveries about the plant immune system, natural variation, root biology, and other areas.
Early history
A. thaliana was first described by Johannes Thal, and later renamed in his honor. (See the Taxonomy section of the main article.) Friedrich Laibach outlined why A. thaliana might be a good experimental system in 1943 and collected a large number of natural accessions. A. thaliana is largely self-pollinating, so these accessions represent inbred strains, with high homozygosity that simplifies genetic analysis. Natural A. thaliana accessions are often referred to as “ecotypes”. Laibach had earlier (1907) determined the A. thaliana chromosome number (5) as part of his PhD research. Laibach's student Erna Reinholz described mutagenesis of A. thaliana with X-ray radiation in 1945.
George Rédei pioneered the use of A. thaliana for fundamental studies, mutagenizing plants with ethyl methanesulfonate (EMS) and then screening them for auxotrophic defects and writing an influential review in 1975. Rédei distributed the standard laboratory accessions ‘Columbia-0’ and ‘Landsberg erecta’.
Gerhard Röbbelen organized the first International Arabidopsis Symposium in 1965. Röbbelen also started the 'Arabidopsis Information Service', a newsletter for sharing information in the community. This newsletter was maintained by A.R. Kranz starting in 1974, and was published until 1990.
Growing interest, 1975-1986
As molecular biology methods progressed, many investigators sought to focus community effort on a common model plant species such as petunia or tomato. This concept changed the emphasis of the long tradition of researchers using diverse agronomically important species such as maize, barley, and peas. The A. thaliana subcommunity espoused an ethos of freely sharing information and materials, and investigators were attracted by the perceived wide-open nature of plant molecular genetics relative to other fields that were better established and thus more “crowded” and competitive. The A. thaliana genome was shown to be relatively small and nonrepetitive, which was an important advantage for early molecular methods. Pioneering A. thaliana studies have used its natural filamentous pathogen Hyaloperonospora arabidopsidis, the model plant-pathogenic bacterium Pseudomonas syringae, and many other microbes. A. thaliana roots are transparent and have a relatively simple radially symmetric cellular structure, facilitating analysis by microscopy.
Molecular cloning, 1986-2000
Cloning of an A. thaliana gene, an alcohol dehydrogenase-encoding locus, was described in 1986, by which time mutations at over 200 loci had been defined.
Genetic linkage maps, QTL populations, and map-based cloning
Development of genetic maps based on scorable phenotypes
and molecular genetic markers facilitated map-based cloning of mutant loci from classical "forward genetic" screens. Growing amounts of DNA sequence data facilitated development and application of such molecular markers. Descriptions of the first successful map-based cloning projects were published in 1992.
Recombinant inbred strain/line (RIL) populations
were developed, notably from a cross of Columbia-0 × Lansberg erecta, and used to map and clone a wide variety of quantitative trait loci.
Efficient genetic transformation
A. thaliana can be genetically transformed using Agrobacterium tumefaciens; transformation was first reported in 1986. Later work showed that transgenic seed can be obtained by simply dipping flowers into a suitable bacterial suspension. The invention/discovery of this 'floral dip' method, published in 1998, made A. thaliana arguably the most easily transformed multicellular organism, and has been essential to many subsequent investigations. Efficient transformation facilitated insertional mutagenesis as described further below.
Floral homeotic genes and the ABC model
A. thaliana geneticists
made important contributions to development of the ABC model of flower development via genetic analysis of floral homeotic mutants.