Exploring the domestication and agricultural potential of wheat wild relatives

Abstract

Crop domestication modified wild plants to suit human needs. This process and subsequent breeding induced genetic bottlenecks in domesticated plants leading to an altered genetic diversity. Ancient diversity has been preserved in crop wild relatives (CWRs). Wheat (Triticum aestivum L.; Triticum durum Desf.) is a staple crop with a long breeding history. The Triticum genepool contains two wild diploid taxa, Triticum urartu and Triticum boeoticum, and two tetraploid wild taxa, Triticum dicoccoides and Triticum araraticum, that harbor beneficial traits. A new approach to leverage the wild relatives’ beneficial traits is de novo domestication - the modification of domestication genes in CWRs via genome editing - which modifies the wild relative in a cultivable crop itself. Prior to de novo domestication, suitable taxa and genotypes for the target environment, target traits for modification and beneficial traits like elevated grain quality need to be determined. The aim of this thesis was to explore the wild Triticum taxa for their agricultural and domestication potential and thus to pave a way for a de novo domestication of wild wheat with beneficial grain quality. Therefore, the beneficial potential of wheat wild relatives for grain quality improvement and its evolutionary change was reviewed. To evaluate the adaptability of wild wheats to the central European climate and identify target traits for a de novo domestication, wild wheat genotypes and for comparison landrace genotypes and modern wheat cultivars were grown in a field in Giessen. Thereafter, they were analyzed for specific grain quality traits to identify changes during domestication and to select wild wheats with superior grain quality for a de novo domestication. The wild wheats showed a good adaptability to the central European climate. Shattering and tight glumes impaired harvest and were proposed as target traits for a de novo domestication. Furthermore, significant lower yields were observed in wild wheats compared to landraces and modern wheat cultivars. Therefore, yield traits were suggested to be modified in a de novo domestication. The grain quality analysis revealed high grain Fe and Zn concentration and a high Grain Protein Content in wild wheats compared to the landrace taxa and modern cultivars. Among the wild wheats, T. araraticum was outstanding for the grain quality traits. Therefore, four T. araraticum genotypes were selected as potential candidates for a de novo domestication. The identification of suitable T. araraticum genotypes with beneficial grain quality traits prepared the first step towards a de novo domestication of the wheat wild relative T. araraticum. Thus wild wheats harbor a potential for de novo domestication that can be leveraged in the future to improve the diversity of the cropping system.