Figure 2

Characteristics of EXPRSS tag-sequences. (A) Uniquely aligned tags to the sense strand of cDNA and genome sequences from all Arabidopsis genes are used to plot tag alignment position as a distance from 3′ end of annotated genes against the frequency of reads mapped. Rectangle selection is shown as inset picture. (B) Example of alternative polyadenylation. A distinct cluster of tags from both full length (blue circle) and short (red circle) sense transcripts of FCA (AT4G16280), which are about 6.5 kb apart. Evidence from cDNA sequences (green arrows) in the TAIR database corroborates short transcripts. Reads from such alternative polyadenylation transcripts result in a long tail in tag alignment frequency distribution presented in A. (C) Frequency distribution of antisense tags aligning to 10 selected transcripts plotted against mapping position as a distance from 5′ end of annotated genes. Each individual abundantly expressing an antisense transcript has a distinct peak of tag alignment suggesting a defined polyadenylation site for antisense transcripts identified through EXPRSS method.