Fig. 4

Motif enrichment analysis in maize and soybean. The upper panel illustrates the composition of tri-nucleotide motifs and the induction of motifs related to solar-UV signature on double strand DNA. Each tri-nucleotide motif is formed by incorporating reference base pairs immediately upstream and downstream to the middle SNP site. Ninety-six motifs are divided into 6 classes based on the substitution types of the SNP. The lightning sign shows the mutation site, and the purple rectangle highlights the motifs related to the solar-UV signature. The middle and lower panels show the frequency of motif in maize and soybean, respectively. For each motif, the left bar is the overall frequency around SNP sites, while the right bar is the overall frequency of the same motif around random sites (an empirical 95th percentile drawn from 100 random sample scenarios). The colored bar indicates the common motif between maize and soybean with a frequency greater than 1/96, and the frequency of motif at SNP sites is higher than that at random sites. The bar with a star on top highlights the motif related to solar-UV signature