Development and Application of Genomic Models for Large-Crop Plant Genomes

Plant genomes vary enormously in size. A part of this variation is generated by polyploidy, which is ubiquitous in the plant kingdom; however, even between closely related, ostensibly diploid species, it can still vary by an order of magnitude. A notable, but not atypical example is the contrast between rice (1 C DNA content of 0.50 pg, equivalent to 450 Mbp) and barley (5.55 pg, 5300 Mbp). The gene content of these two species is thought to be rather similar, numbering something under 40,000, depending on the gene prediction program employed [1]. Thus, much of the difference in DNA content is made up of nongenic DNA—in particular, retrotransposons