Domestication and crop evolution of wheat and barley: Genes, genomics, and future directions

Abstract

Wheat and barley are two of the founder crops of the agricultural revolution that took place 10,000 years ago in the Fertile Crescent and both crops remain among the world's most important crops. Domestication of these crops from their wild ancestors required the evolution of traits useful to humans, rather than survival in their natural environment. Of these traits, grain retention and threshability, yield improvement, changes to photoperiod sensitivity and nutritional value are most pronounced between wild and domesticated forms. Knowledge about the geographical origins of these crops and the genes responsible for domestication traits largely pre‐dates the era of next‐generation sequencing, although sequencing will lead to new insights. Molecular markers were initially used to calculate distance (relatedness), genetic diversity and to generate genetic maps which were useful in cloning major domestication genes. Both crops are characterized by large, complex genomes which were long thought to be beyond the scope of whole‐genome sequencing. However, advances in sequencing technologies have improved the state of genomic resources for both wheat and barley. The availability of reference genomes for wheat and some of its progenitors, as well as for barley, sets the stage for answering unresolved questions in domestication genomics of wheat and barley.

Comprehensive analysis of Q gene near‐isogenic lines reveals key molecular pathways for wheat domestication and improvement

“…To study the effects of Q on agronomic characters, we generated three NILs in the genetic background of BW, and refer to these as BW‐ Q , BW‐ Q mut , and BW‐ q . BW ‐Q and BW ‐q carried the domesticated Q allele and the primitive q allele that was originally derived from wild emmer wheat (Faris, ; Haas et al , ), whereas the Q allele in BW‐ Q mut contained a guanine to adenine mutation in the first base of the second exon, which generates a premature stop codon leading to a truncated peptide of 138 amino acids (aa) relative to the full length protein of 447 aa (Figure S1a). The three NILs showed similar plant phenotypes at vegetative stages (Figure S1b).…”

Where the Wild Things Are: Transposable Elements as Drivers of Structural and Functional Variations in the Wheat Genome

“…Crop domestication involved recurrent selection to increase the frequency of desirable traits, leading after thousands of years to dramatic loss in genetic variation (Bevan et al, 2017). Wild relatives of domesticated wheat are recognized as a great potential source for crop improvement in face of growing global population, environmental changes and increasingly challenging growing conditions (Bevan et al, 2017;Haas et al, 2019). Due to their activity and involvement in genomic rearrangements, TEs are important source of intra-specific genetic variation (Dubin et al, 2018).…”

Unveiling the Actual Functions of Awns in Grasses: From Yield Potential to Quality Traits

“…However, these results are not strictly conclusive since cultivated rice typically has short or non-existent awns, although long-awn variants exist, and grain shattering is not a common trait in cultivated rice. Furthermore, grain dispersal by awns has been suppressed in some wheat and barley cultivars by insertion of the grain retention trait, which is governed by various regulators, including naked caryopsis ( nud ) and thresh-1 genes in barley or Tenacious glumes ( Tg ) locus and the Q allele in wheat [ 72 ]. These findings emphasize the undocumented role of awns in grain shattering of some cereals and reinforce the need for additional research in other grass species to learn whether and how awns are linked with grain shattering.…”