Dot plot analysis of the I2 locus between tomato and potato. The vertical line represents the I2 locus in tomato cultivar Heinz 1706, and the horizontal line represents the I2 locus in potato cultivar DM. The positions for nine sub-loci (S-1 to S-9) and important markers are shown in both the horizontal and vertical lines. The numbers in brackets after the sub-locus name are the number of I2 homologues at corresponding positions. No large duplications were found, and duplications were mainly limited to the I2 sequences but not their flanking regions.