Novel quantitative trait loci underlying major domestication traits in tetraploid wheat

Wheat domestication and subsequent evolution under domestication occurred since the dawn of agriculture and caused significant genetic changes that affected plant morphology, physiology and phenology. The majority of these traits are quantitative traits controlled by many genes. Correspondingly, the main goal of the current study is genetic dissection of the key domestication trait (brittle rachis) and traits evolved under domestication, based on quantitative phenotyping. Genetic mapping of quantitative trait loci (QTL) affecting brittle rachis, threshability, threshing efficiency, spike harvest index and kernel weight was conducted using a recombinant inbred lines population derived from a cross between Triticum durum and wild emmer wheat. Using a new quantitative phenotyping approach, we discovered novel QTLs underlying rachis fragility, spike threshability and other domestication-related traits and confirmed some of the known putative locations for QTLs affecting these traits. Overall, the number of domestication-related QTLs mapped to the A genome was twofold higher than those found on the B genome, in accordance with the concept of ‘genome asymmetry’, implying that the A genome is dedicated to the control of morphological traits, house-keeping metabolic reactions and yield components. Our results add a new dimension to this important concept and contribute to a better understanding of the initial steps of domestication evolution of cereals.