In This Issue

shape, and yield remain unclear. Cheng Qin et al. (pp. 5135–5140) generated reference genome sequences for the cultivated pepper Zunla-1 (Capsicum annuum L.), grown in China’s Guizhou Province, and its wild progenitor Chiltepin (C. annuum var. glabriusculum), grown in northcentral Mexico. The authors report that greater than 81% of the 3.26 Gb-sized pepper genome is composed of mobile genetic elements called transposons, the genomic insertion of which likely occurred around 0.3 million years ago, leading to recent genome expansion in the pepper family’s evolutionary history. Phylogenetic analysis suggested that peppers likely diverged from potatoes and tomatoes—peppers’ kin—around 36 million years ago. In addition, the authors scanned the genomes of 18 major cultivated pepper varieties for signs of artificial selection, and identified putative domestication-related genes, which might explain differences between wild and cultivated peppers; among the genes were those potentially linked to shortened seed dormancy, enhanced pathogen and stress resistance, and increased shelf life. Further, the authors identified pepper-specific gene duplications and a gene-dosage compensation mechanism linked to the buildup of capsaicinoids, which lend some pepper varieties their pungency. According to the authors, the genome sequences might help improve the effectiveness of pepper breeding programs. — P.N.