A Pangenome of Tetraploid Wheat Reveals the Genetic Architecture Underlying Domestication and Genomic Diversity for Breeding

Tetraploid wheat (Triticum turgidum L., BBAA), a key pasta crop, serves as an untapped genetic resource with rich genomic diversity for hexaploid bread wheat improvement. Here we de novo assembled 12 genomes spanning all 10 recognized tetraploid wheat (genome BBAA) subspecies, and a graph-based pangenome was constructed. Chromosome rearrangements drove subgenome asymmetry and shaped genomic divergence, with an average of 0.25 million structural variations per accession, predominantly attributable to transposon activity. Using 736 globally distributed tetraploid wheat accessions, we identified locally adapted subgroups with untapped breeding potential and discovered a novel retrotransposon‑induced loss‑of‑function Btr1-A allele responsible for convergent adaptation of non-brittle rachis. Genome-wide association studies identified 287 loci associated with 32 traits. A homeodomain-leucine zipper transcription factor HAT14-B that enhances both spikelet number and grain size was identified. This subspecies-wide pangenome enriches Triticeae AB subgenome resources and facilitates the discovery and application of agronomically important genetic variations.