Figure 4

Repetitiveness of small RNA (sRNA) reads measured across sizes. The number of total reads for all uniquely and nonuniquely mapping genomic sequences divided into ribosomal RNA- or transfer RNA-derived and other (also known as "good") categories for each size class from 18 to 34 nt across 51 publicly available Arabidopsis sRNA libraries. For each size class, structural RNA-derived reads are more likely to map nonuniquely mapping genomic sequences (that is, to more than one genomic location), whereas good reads are more likely to map uniquely mapping genomic sequences (that is, to one genomic location).