Domestication effects on wheat morphology and production

Wheat is one of the world's most important food crops, and increasing wheat production is an important solution to hunger. From its ancient wheat ancestors to the edible modern varieties available to people today, wheat has undergone a long evolutionary process involving domestication, chromosome doubling, selective breeding, and the Green Revolution. During these historical processes, wheat morphology has changed dramatically. We have also found that wheat crop improvement can be achieved by domesticating the phenotype for the purpose of increasing yield. However, phenotypic improvement in wheat has encountered a number of difficulties. The most important of these is the domestication bottleneck. Namely, the wild traits of wheat have been lost in evolution and its germplasm pool has been shrinking in domestication selection.
Therefore, we conducted the present project focusing first on the wheat morphological traits that have emerged and disappeared during the evolutionary process. Secondly, we took the values of these traits that wheat had possessed and carried out modelling work to predict the ideal high yielding wheat based on existing trait variation. We also conducted experiments to investigate the loss of loci associated with certain yield traits in wheat during the evolution of domestication, as well as changes in individual competitiveness during wheat domestication.
The results showed that there was a loss of morphological traits in wheat during domestication, but natural selection and genetic mutations also created new domains of phenotypic trait values. Morphological traits of wheat showed different characteristics at different historical periods. Some traits have risen or declined in one direction during wheat evolution, others have changed only at certain stages; still others have shown opposite trends before and after the period. For one of the important wild traits, awns, we also found the locus associated with its disappearance during landrace improvement. Using these morphological traits to model and optimise their values, we created virtual ideotypes of wheat. They were taller and had more tilers than the original wheat, which also resulted in yield gains. However, these yield
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Abstract
advantages were not apparent under high density planting. Finally, we found that individual competitiveness of wheat increased during domestication. Higher individual competitiveness in domesticated wheat may be detrimental to the efficiency of population yield at high densities.
Our results elucidate the relationship between wheat phenotype, domestication and yield. This helps agronomists to better understand crop domestication, as well as for future breeding efforts.