Plant Genome and Arabidopsis thaliana

A genome is defined as the complete complement of DNA present in an organism, including every gene together with all the intergenic (non-gene) regions between them, and it specifies the entirety of an organism's biological information. A eukaryotic plant cell is unusual in carrying not one but three genetically distinct genomes simultaneously: the nuclear genome, contained within the cell's main nucleus; the mitochondrial genome; and the chloroplast (plastid) genome, which is found only in plant and algal cells, not in animal cells. Arabidopsis thaliana, commonly called thale cress or mouse-ear cress and a member of the mustard family, became the standard model organism for studying the nuclear plant genome, and holds the distinction of being the first flowering plant species to have its entire genome fully sequenced. Several practical attributes make it exceptionally well suited to genetic and molecular research: it is diploid with a small genome of 2n=10 chromosomes, and its nuclear DNA has unusually little repetitive sequence, with over 60% of it coding directly for protein; being a small, self-fertilising, annual long-day plant with an extremely short life cycle of only about six weeks, it produces large numbers of seeds and can go through several generations in a single year, greatly speeding up genetic analysis; it is easy to grow in a standard laboratory setting, mutations are easy to induce in it, an extensive library of genomic resources already exists for it, and genetic transformation (introducing new DNA into it) can be carried out routinely. Its two regions of nucleolar-organiser ribosomal DNA, which code …