Fig. 4.

Distribution of the GC content in the third codon position of CDSs of different plant species. All grasses have a broad distribution with two peaks whereas the dicots have a unimodal distribution. All CDS sequences except corn (we used sequences described in this paper) and Arabidopsis (we used TAIR annotation) were downloaded from the J. Craig Venter Institute (JCVI, formerly known as TIGR) ftp site ftp://ftp.tigr.org/pub/data/plantta/. The number of unique transcripts for each species is: switchgrass 7,638, Arabidopsis 27,983, poplar 12,687, canola 10,709, Medicago 20,414, cotton 24,797, corn 10,084, rice 49,870, sorghum 20,714 and wheat 62,121