About the cover
The cover shows women threshing quinoa in Perus highlands. In this issue, Mark Tester and colleagues report a reference genome for quinoa (Chenopodium quinoa), a highly nutritious crop that can grow under a wide range of environmental conditions. Long-read sequencing combined with optical, chromosome-contact and genetic maps was used to generate the allotetraploid genome. The authors also sequenced the genomes of additional diploid and tetraploid Chenopodium species, characterizing genetic diversity and the evolution of sub-genomes in the crop. In the process, Tester and colleagues identified a transcription factor that regulates the biosynthesis of bitter-tasting saponins in quinoa, as well as markers that might be used to develop sweet commercial varieties. Cover image: Lynn Johnson/National Geographic Creative.