Genome Sequencing and Plant Genome Projects

A genome is the complete set of genes that, together, determine every characteristic of an organism - and 'genome' is not a single, uniform concept, since a plant cell actually carries three distinct genomes at once: the nuclear genome, the mitochondrial genome, and, uniquely to plants and algae, the plastid genome. Any given plant genome is a mix of functional, protein-coding DNA and non-expressive DNA, and its overall size can be expressed either directly, as a total base-pair count, or as a standardised measure called the c-value. A genome project is a large, coordinated research effort to sequence and analyse an organism's entire genome, typically by comparing that sequence for homology against other, already-sequenced species; among plants, such projects have so far been carried out in Chlamydomonas (an alga), Arabidopsis thaliana, rice and maize - a deliberately varied set spanning algae, a model laboratory plant, and two major food crops. A related, more applied idea introduced here is genetic 'barcoding': just as a product barcode is a short, standardised, machine-readable code that instantly identifies an item and its details at a supermarket checkout, a genetic barcode is a short, standardised DNA s …