| Summary: | Wheat is an important crop and represents an essential component of the global food security. Hybrid wheat, which currently occupies only a niche sector in commercial wheat production because of several barriers could help facing the challenges of a growing population and climate changes.
This PhD thesis focused particularly on the improvement of the hybrid seeds production based on an efficient cytoplasmic male sterility system (CMS). The first part of the project consisted of the study of wide range of wild relatives (from the Aegilops, Secale, Thinopyrum and Triticum genus) as potential source of male fertility restoration genes against T. timopheevii cytoplasm. Their genomes were tested through various type of material including amphidiploids and introgression lines. Different strategies were used to reduce the impact of the post-zygotic barriers. Characterization of the fertile hybrid lines was carried out by combining cytogenetics analysis (GISH and FISH) with molecular genotyping (KASP markers). We identified five new restorer chromosomes. The chromosomes 4RL of S. anatolicum and 6G of T. timopheevii were restoring partially the male fertility in the presence of T. timopheevii cytoplasm. High level of restoration was observed in presence of the chromosomes 1At of T. timopheevii, 5Ssh and 6Ssh of Ae. sharonensis.
The second part of the project focused on the development of a new CMS system based on Ae. sharonensis cytoplasm. Wheat male sterile alloplasmic lines were successfully developed. Male fertile alloplasmic lines were produced, indicating the presence of restorer genes into wheat genome against Ae. sharonensis cytoplasm. The wide set of wheat / Ae. sharonensis addition, substitution and translocation lines produced could be source of new restorer factors.
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