About the cover: The Presence and Absence Variants (PAVs) are a major source of genome structural variations that are useful in functional genomics and plant breeding. Using the next generation sequencing technology, Zhang et al. (pp. 24–37) identified a large number of PAVs in the C4-model plant Sorghum bicolour. They characterized 51 large-sized PAVs (>30 kb) that affect a total size of 2.92 Mb and contain 202 genes in a panel of 96 sorghum inbred lines.