Growth and Gaps in Plant Genome Size Data

The c. 2400-fold diversity of plant nuclear genome sizes has long intrigued biologists who have sought to understand how and why such variation exists. Now, in the post-genomics world, challenged by climate and environmental change, the need to have access to this key biodiversity character is more important than ever as large comparative studies reveal the impact of genome size at the genomic, ecological and evolutionary levels.

To meet this growing need is the Plant DNA C-values database, (http://data.kew.org/cvalues/) which provides an easily accessible one stop shop of published data on plant genome sizes. The database first went live in 2001 and the latest version (release 6.0, December 2012) contains data for over 7,500 species making it the largest database of its kind. Indeed, its value is demonstrated by the number of hits it receives (now over 100 per day), which have increased by over 150% since 2001.

The database includes genome sizes for all major land plant groups which comprise angiosperms, gymnosperms, monilophytes (ferns and horsetails), lycophytes, and bryophytes. Nevertheless, representation is highly uneven, ranging from no data for hornworts (a potentially key group of bryophytes which are considered to be sister to all vascular plants) to over 25% of gymnosperm species. The challenge for the future will be to set and achieve realistic targets to improve representation of genome size data across all groups of land plants and hence to uncover the full diversity of plant genome sizes.