Genomics of crop wild relatives: expanding the gene pool for crop improvement

Abstract

Plant breeders require access to new genetic diversity to satisfy the demands of a growing human population for more food that can be produced in a variable or changing climate and to deliver the high-quality food with nutritional and health benefits demanded by consumers. The close relatives of domesticated plants, crop wild relatives (CWRs), represent a practical gene pool for use by plant breeders. Genomics of CWR generates data that support the use of CWR to expand the genetic diversity of crop plants. Advances in DNA sequencing technology are enabling the efficient sequencing of CWR and their increased use in crop improvement. As the sequencing of genomes of major crop species is completed, attention has shifted to analysis of the wider gene pool of major crops including CWR. A combination of de novo sequencing and resequencing is required to efficiently explore useful genetic variation in CWR. Analysis of the nuclear genome, transcriptome and maternal (chloroplast and mitochondrial) genome of CWR is facilitating their use in crop improvement. Genome analysis results in discovery of useful alleles in CWR and identification of regions of the genome in which diversity has been lost in domestication bottlenecks. Targeting of high priority CWR for sequencing will maximize the contribution of genome sequencing of CWR. Coordination of global efforts to apply genomics has the potential to accelerate access to and conservation of the biodiversity essential to the sustainability of agriculture and food production.

Keywords: crop wild relatives; genomics; plant genetic resources.

Figure 1

Relationships between high priority crop wild relatives (CWRs). Numbers indicate the number of high importance CWR species within each plant group.

Figure 2

Crop wild relatives. These species represent sources of novel variation for use in crop improvement. (a) barley (wild barley (Hordeum spontaneum) growing near Allepo, Syria); (b) coffee (Coffea brassii), photograph by Australian Tropical Herbarium; (c) rice (Oryza A genome wild populations, growing near Mareeba, Australia); (d) grape (Cissus antarctica).