A genomic approach to the evolution, diversification and domestication of the genus Citrus

Abstract

Citrus is a highly diverse genus within the Aurantioideae subfamily that comprises a still undetermined number of pure species, natively found in a vast territory that extends from India to Japan and Australia. Indeed, a pivotal unsolved issue concerning the genus Citrus is related to the taxonomy and evolution of these species, obscured by the frequency of the admixed Citrus germplasm and its huge phenotypical diversity. Besides pure species, countless citrus cultivars of commercial interest, such as mandarins, oranges, grapefruits and lemons, have been traditionally included in this genus. Commercial citrus are the product of several interspecific crosses between these pure species, that occurred during the first events of Citrus domestication. In addition, a genome-wide analysis has recently provided the backbone of the Citrus phylogeny. This study suggests that the native current species diverged from an ancestral citrus in a relatively rapid radiation triggered by a global climate change, about 8 million years ago during the Late Miocene. Understanding the processes that shaped the evolution and subsequent domestication of the genus will prove useful for citrus breeders while providing novel insights in the field of plant genome evolution.