In this issue,Wu et al.(2019) describe the largest whole-genome resequencing dataset published to date for rapeseed (Brassica napus),an allopolyploid crop species that originated just a few thousand years ago under anthropogenic influence and rapidly evolved into one of the world's most important oilseed crops.In almost 1000 accessions spanning species-wide germplasm for oilseed rape,a comprehensive analysis of sequence diversity related to flowering-related traits uncovered selective sweeps associated with eco-geographic adaptation and human selection,attributable particularly to divergence among homoeologs of key flowering-time regulation and ethylene synthesis/ signaling genes.The authors further extend their analysis to retrospective,genome-based documentation of diversity footprints that trace the global expansion of the species across a century of breeding.The study contributes not only a rich catalog of genome-wide diversity for genetic analysis and future breeding of important agro-econornic traits but also a unique conceptional framework for ongoing selective adaptation of oilseed rape crops to emerging challenges presented by chang ing climatic conditions in key production areas.Selective sweeps were found to contain genes involved in stress adaptation and development,especially flowering time,indicating that climatic adaptation both in terms of local stress factors and of life-cycle adaptation was the major factor underlying agronomic selection for improved seed yield.
展开▼
