Arabidopsis Thaliana - Use As A Model Organism

Use As A Model Organism

Botanists and biologists began to research A. thaliana in the early 1900s, and the first systematic collection of its mutations was performed around 1945. It is now widely used for studying plant sciences, including genetics, evolution, population genetics, and plant development. It plays the role in plant biology that mice and fruit flies (Drosophila) play in animal biology. Although A. thaliana has little direct significance for agriculture, it has several traits that make it a useful model for understanding the genetic, cellular, and molecular biology of flowering plants.

The small size of its genome makes Arabidopsis thaliana useful for genetic mapping and sequencing — with about 157 mega base pairs and five chromosomes, arabidopsis has one of the smallest genomes among plants. It was the first plant genome to be sequenced, completed in 2000 by the Arabidopsis Genome Initiative. The most up-to-date version of the A. thaliana genome is maintained by the Arabidopsis Information Resource (TAIR). Much work has been done to assign functions to its 27,000 genes and the 35,000 proteins they encode. Post-genomic research, such as metabolomics, has also provided useful insights to the metabolism of this species and how environmental perturbations can affect metabolic processes.

The plant's small size and rapid life cycle are also advantageous for research. Having specialized as a spring ephemeral, it has been used to found several laboratory strains that take about six weeks from germination to mature seed. The small size of the plant is convenient for cultivation in a small space, and it produces many seeds. Further, the selfing nature of this plant assists genetic experiments. Also, as an individual plant can produce several thousand seeds; each of the above criteria leads to A. thaliana being valued as a genetic model organism.

Plant transformation in arabidopsis is routine, using Agrobacterium tumefaciens to transfer DNA to the plant genome. The current protocol, termed "floral-dip", involves simply dipping a flower into a solution containing Agrobacterium, the DNA of interest, and a detergent. This method avoids the need for tissue culture or plant regeneration.

The arabidopsis gene knockout collections are a unique resource for plant biology made possible by the availability of high-throughput transformation and funding for genomics resources. The site of T-DNA insertions has been determined for over 300,000 independent transgenic lines, with the information and seeds accessible through online T-DNA databases. Through these collections, insertional mutants are available for most genes in arabidopsis.

Finally, the plant is well suited for light microscopy analysis. Young seedlings on the whole, and their roots in particular, are relatively translucent. This, together with their small size, facilitates live cell imaging using both fluorescence and confocal laser scanning microscopy. By wet mounting seedlings in water or in culture media, plants may be imaged uninvasively, obviating the need for fixation and sectioning and allowing time-lapse measurements. Fluorescent protein constructs can be introduced through transformation. The developmental stage of each cell can be inferred from its location in the plant or by using fluorescent protein markers, allowing detailed developmental analysis.

TAIR and NASC are curated sources for diverse arabidopsis genetic and molecular biology information, and also provide numerous links, for example, to databases that store the results of hundreds of genome-wide gene expression profile experiments. Seed and DNA stocks can be obtained from NASC or the Arabidopsis Biological Resource Center.