Direct introgression of untapped diversity into elite wheat lines

Ancestral wheat relatives can enrich the genetic diversity of modern cultivars and contribute to stress adaptation. A meta-genome-wide association study identifies the exotic genome footprints in a wheat pre-breeding population, as well as some exotic-specific agronomic traits. The effective utilization of natural variation has become essential in addressing the challenges that climate change and population growth pose to global food security. Currently adopted protracted approaches to introgress exotic alleles into elite cultivars need substantial transformation. Here, through a strategic three-way crossing scheme among diverse exotics and the best historical elites (exotic/elite1//elite2), 2,867 pre-breeding lines were developed, genotyped and screened for multiple agronomic traits in four mega-environments. A meta-genome-wide association study, selective sweeps and haplotype-block-based analyses unveiled selection footprints in the genomes of pre-breeding lines as well as exotic-specific associations with agronomic traits. A simulation with a neutrality assumption demonstrated that many pre-breeding lines had significant exotic contributions despite substantial selection bias towards elite genomes. National breeding programmes worldwide have adopted 95 lines for germplasm enhancement, and 7 additional lines are being advanced in varietal release trials. This study presents a great leap forwards in the mobilization of GenBank variation to the breeding pipelines.

Automated summary

Through a strategic crossing scheme and genome-wide association study, this research demonstrates the importance of exotic genes in wheat pre-breeding lines and their impact on agronomic traits. The study highlights the essential role of utilizing natural genetic variation in addressing challenges to global food security posed by climate change and population growth.