|
The genus Arabidopsis is a member of the Brassicaceae (mustard or crucifer) family in the tribe Sisymbriae that contains several species including the most well-known Arabidopsis thaliana. This particular species has emerged as a model plant for studies in classical and molecular genetics, developmental biology, physiology, biochemistry and functional genomics for a variety of reasons. These include the facts that:
- Arabidopsis develops, reproduces and responds to disease and environmental stresses in ways comparable to many crop plants.
- Arabidopsis plants are relatively small making it easy and inexpensive to grow them under a variety of research conditions.
- Arabidopsis thaliana possesses a relatively small genome marked by a remarkable absence of highly and moderately repetitive sequences. This feature has allowed researchers to adopt saturation mutagenesis strategies and/or map-based cloning strategies not possible in other plants with genomes containing significant proportions of repetitive DNA.
- Arabidopsis has a short non-seasonal generation time (5 weeks) and the ability to produce thousands of seeds per plant. These features have facilitated the extensive genetic analyses needed to map individual gene traits.
- Arabidopsis is autogamous (self-fertile), which makes the maintenance of homozygous lines straightforward, and capable of being cross-pollinated, which makes genetic crosses and gene mapping possible.
- Arabidopsis thaliana is a diploid with a small number of chromosomes (five). This has facilitated the identification of recessive traits and allowed researchers to avoid the complications of varying gene dosages encountered in many other plant species.
- Arabidopsis is readily transformed by vacuum infiltration with Agrobacterium tumefaciens containing T-DNA based binary vectors. This has allowed researchers to analyze the phenotypic variations associated with overexpression of endogenous and exogenous proteins in intact plants as well as the visual expression patterns of promoter: reporter genes in intact cells.
- Arabidopsis mutants can be readily generated with many different chemical and biological mutagens that randomly alter genomic DNA sequences. This feature has made it possible to generate and screen large mutant collections of progeny for phenotypic changes derived from single nucleotide changes, T-DNA insertions or transposon insertions within protein coding sequences.
Given these biological highlights, concerted efforts have focused on developing and integrating genetic linkage maps, cytological maps and physical maps for the Arabidopsis genome, sequencing this plant's genome and on defining loci needed for normal growth and development. The now completed sequence of the Arabidopsis thaliana genome as well as the many genomic DNA tools derived from this effort (complete contig maps, YAC clones, sequence annotations) and mRNA expression tools (cDNA libraries, EST sequences) is assembled and readily accessed at http://www.arabidopsis.org/. With the many physiological functions shared between this species and others with more complex genomes and prolonged life cycles, there is no doubt that Arabidopsis will serve more and more as a critical resource for defining genomic functions of sequences involved in plant responses to biotic and abiotic assaults. Further descriptions of Arabidopsis and its biochemical pathways are available at http://www.aspb.org/publications/arabidopsis/toc.cfm .