Identification of variation in adaptively important traits and genome-wide analysis of trait–marker associations in Triticum monococcum

Einkorn wheat Triticum monococcum (2n=2x=14, A(m)A(m)) is one of the earliest domesticated crops. However, it was abandoned for cultivation before the Bronze Age and has infrequently been used in wheat breeding. Little is known about the genetic variation in adaptively important biological traits in T. monococcum. A collection of 30 accessions of diverse geographic origins were characterized for phenotypic variation in various agro-morphological traits including grain storage proteins and endosperm texture, nucleotide-binding site (NBS) domain profiles of resistance (R) genes and resistance gene analogues (RGAs), and germination under salt and drought stresses. Forty-six SSR (single sequence repeat) markers from bread wheat (T. aestivum, 2n=6x=42, AABBDD) A genome were used to establish trait-marker associations using linear mixed models. Multiple significant associations were identified, some of which were on chromosomal regions containing previously known genetic loci. It is concluded that T. monococcum possesses large genetic diversity in multiple traits. The findings also indicate that the efficiency of association mapping is much higher in T. monococcum than in other plant species. The use of T. monococcum as a reference species for wheat functional genomics is discussed.