The quest for suitable reference standards in genome size research

Abstract

in the molecular genomics era, as the flood gates opento deliver a deluge of DNA sequence data, knowledge of thetotal amount of DNA that comprises an organism’s genome(5 genome size) remains vital for many diverse fields of biol-ogy. Indeed, it may be considered to be a key biodiversitycharacter with both practical and biological consequences forthe organism. Knowledge of genome size is important, forexample, in ongoing and planned sequencing programs toassess costs and to know how much DNA to sequence, or fordetermining how many large insert clones (e.g., bacterial arti-ficial chromosomes [BACs] or fosmids) are needed for con-structing genomic libraries. In addition, various genetic finger-printing tools (e.g., microsatellites and AFLPs) have beenshown to be sensitive to genome size so knowledge of thischaracter is important before embarking on such studies.From a biological perspective variation in genome size hasbeen shown to have diverse yet predictable consequences foran organism, influencing, for example, how it will respondto changes in carbon dioxide, rising temperatures, andpollution (1).While people have been estimating genome sizes in plantsand animals for over 50 years, the last decade has seen a hugegrowth in the number of estimates published, not only to pro-vide data for molecular studies but also for large scale compar-ative analyses seeking to understand the biological and evolu-tionary significance of the 40,000-fold range of genome sizesencountered across eukaryotes (2). Indeed, data are now avail-able for over 10,000 species, accessible through the internetin three databases (Animal Genome Size Database—www.genomesize.com; Fungal Genome Size Database—www.zbi.ee/fungal-genomesize; and the Plant DNA C-values Database—http://data.kew.org/cvalues).