Introduction
Model organisms can be described as organisms that are capable of being used in laboratories studies to conduct certain research or experiments. “Arabidopsis thaliana is a small flowering plant that belongs to genus Arabidopsis, a member of the Brassica (mustard or crucifer) family in the tribe Sisymbriae” (Meyerowitz, 1994). It has emerged as a model plant for studies in classical and molecular biology, physiology, biochemistry, and functional genomics (Meyerowitz, 1994).
The plant has been suitable for studies in molecular, cellular, and genetic biology because of its several unique features. The small sizes of Arabidopsis make them easy to grow since they take less space hence lesser cost. It has a relatively small genome and has a short non-seasonal generation time of about 5 weeks. “Arabidopsis is readily transformed by vacuum infiltration with Agrobacterium tumefaciens containing T-DNA based binary vectors; and mutants can be readily generated with many different chemical and biological mutagens” (Keck and Craver, 2010, p.1). This paper concentrates on three characteristics, which include those listed below.
A Relatively Small Nuclear Genome
“The nuclear genome of Arabidopsis Thaliana is unusually small for a flowering plant. It also has a remarkably little dispersed repetitive DNA,” (Meyerowitz, 1994, p.21). “These properties facilitate a series of different types of experiments in molecular biology and have allowed facile cloning of many Arabidopsis genes by methods that would be difficult or impossible if the genome was larger or more typical in its content of repetitive sequences” (Meyerowitz, 1994, p. 21).
The genome size is (7xlO7 base pairs per haploid) of about a hundredth of the size of higher plants (Komaki et al., 1998). The utility of having such a small genome is that chromosome walks, which require repeated screening of genomic libraries and library screens in general can be done with much less effort than with plants that have genomes of more typical size (Meyerowitz,1994). The small genome size has potentiated several other methods of gene cloning, for instance, subtraction hybridization, in which genetic mutations are deleted and the DNA deleted is identified by hybridizing an excess of mutant plant DNA to wild-type fraction not hybridized by the mutant genome (Meerowitz,1994). “The feature has also allowed researchers adopt saturation mutagenesis strategies and/or map-based cloning strategies not possible in other plants” (Keck and Craver, 2010, p.1).
Arabidopsis is Convenient and Inexpensive to Grow
The Plant Arabidopsis Thaliana is convenient and easy to grow. It grows readily in defined solid or liquid media, allowing rapid screening for seedling defects, recovery of transformants, and propagation of pathogen-free tissues (Weigel and Glazebrook, 2002). This makes it possible for it to be grown in confined laboratory environments under various researched conditions. It has convenient genetic properties such as a short generation time and prolific seed production (Meyerowitz, 1994). It matures within 6-8 weeks and produces thousands of seeds per plant facilitating extensive gene analysis for mapping individual gene plants.
Easy access of Readily Generated Mutants
The mutants of Arabidopsis mutants are easy to develop from several different mutagens that change the genomic DNA sequences (Keck and Craver, 2010, p.1). The mutagens could take biological or chemical nature. Because the Arabidopsis genome is largely generic, a high proportion of transformants when made genetically homozygous for the inserted foreign DNA, show new mutations caused by introduced DNA. This allows molecular cloning of the mutated gene by use of probes to the foreign DNA (Meyerowitz, 1994).
The availability of the complete genome sequence and the ease of generating large populations of transformed plants make Arabidopsis thaliana an excellent plant system for the isolation of genes and regulatory elements through T.DNA genotypes (Jain & Brar, 2009). More than 320,000 insertional mutations are available in the Arabidopsis Thaliana Columbia genotype, which are potential sources for the identification of genes and regulatory elements (Jain & Brar, 2009). To date, at least 19,000 flanking sequence tags (FSTs) have been identified to facilitate reverse and forward genetics applications in the Columbia genotype (Kaul et al., 2000, p. 796). In addition, “mutant stocks are available in large numbers from a variety of stock centers such as The Arabidopsis Information Resource” (Kaul et al., 2000, p. 796).
Contribution of Social and Institutional Factors
Various social and institutional factors have contributed to the status of the Arabidopsis as a model organism. The advantageous characteristic of the plant has stimulated the growth of an interested scientific community, which has researched its biological processes and disseminated information on the characters of the genes.
There have been several writings, reviews, reports, and discussions on Arabidopsis sparking the interests of hundreds of scientists resulting in the development of a harmonized Arabidopsis research community. The emergence of plant molecular biology as a new discipline drew the interest of scientists to the Arabidopsis further enhancing its status as a model organism.
Granting agencies around the world have also realized the potential of the Arabidopsis and provided financial aid and administrative support for individual research projects, workshops, and community-wide resources such as stock-centers, databases, and The EST projects (Meyerowitz, 1994).
The organization of the Arabidopsis community with elected representatives on the international level is another social factor and so is the presence of electronic media for the dissemination of information and resources via the internet and online discussions.
Reference List
Jain, S. M., & Brar, D. S. (2009). Molecular techniques in crop improvement. Dordrecht: Kluwer Academic Publishers.
Kaul, S et al. (2000). Analysis of the genome sequence of the flowering plant Arabidopsis thaliana: The Arabidopsis Genome Initiative. Nature International Weekly Journal of Science 408(1), 796-815. Web.
Keck, W., and Craver, R. (2010). About Arabidopsis: Functional Genomics of Arabidopsis P450s. Web.
Komaki, M., Okada, K., Nishono, E. and Shimura, Y. (1998) Isolation and characterization of novel mutants of Arabidopsis thaliana defective in flower development. Great Britain: The Company of Biologists Limited.
Meyerowitz, E. (1994). Arabidopsis. Plainview, NY: Cold Spring Harbor Laboratory Press.
Weigel, D., & Glazebrook, J. (2002). Arabidopsis: A laboratory manual. Cold Spring Harbor, N.Y: Cold Spring Harbor Laboratory Press.