Genetic studies of new grains improved with quality traits

In a global context increasingly focused on sustainability and food quality, the search for sustainable and nutrient-rich raw materials is gaining growing interest. In cereal cultivation, worldwide researchers are shifting their focus to ancient cereals and wild species of domesticated crops. Among these, Aegilops caudata, a wild species, represents a promising genetic resource due to its nutritional characteristics that make it valuable for wheat improvement. Specifically, Aegilops caudata has been used to create amphiploid lines useful for studying qualitative traits such as β-glucan content, a key compounds for human health. Chapter I of this thesis analyzes a key gene in β-glucan synthesis, the cellulose synthase CslF6 gene, by determining the gene sequence and protein structure in Ae. caudata, highlighting evolutionary differences compared to other grass species and examining how variations in the amino acid sequence may influence the β-glucan content. Comparative analysis with other monocots revealed significant similarities with the wheat genome, with variations in amino acid motifs within the catalytic portions of the polypeptide chain, suggesting potential unique functional adaptations for Ae. caudata. Chapter II explores the role of the CslF6 gene in β-glucan synthesis, the total β-glucan content, the glycosidic linkages within the β-glucan structure, and the profile of major oligosaccharides in bread and durum wheat genotypes, wild parental species (Aegilops caudata and Dasypyrum villosum), and their hybrids. The analysis of CslF6 gene expression revealed a correlation between gene expression and β-glucan accumulation. The results indicate that wild species, such as Ae. caudata and Dasypyrum villosum, have a higher β-glucan content compared to wheat, and hybrids show a significant increase in β-glucan levels. Additionally, through glycomics analysis, the study highlighted differences in the monosaccharide composition of the cell wall and the glycosidic linkages in the analyzed genotypes, providing new tools for the selection of wheat lines with high β-glucan content. Chapter III shifts the focus on two important wheat qualitative traits: protein content (GPC) and yellow index (YI), which are critical for pasta production. The study, conducted on 144 tetraploid wheat accessions (Triticum turgidum L.), identified superior alleles associated with these qualitative traits through a Genome-Wide Association Study (GWAS). The analysis identified several association regions (QTLs) between SNP markers and the traits considered (GPC and YI). Bioinformatics analysis revealed candidate gene sequences co-localized within these QTL regions. Notably, a key gene involved in nitrogen metabolism, Glutamine synthetase 2 (GS2), and a key gene for carotenoid biosynthesis, Phytoene synthase 1 (Psy-A1), were identified. Furthermore, the analysis led to the identification of new haplotypes, contributing to a better understanding of the genetic mechanisms controlling protein content and yellow color in wheat, facilitating the development of superior wheat varieties. These three studies, while addressing different aspects of wheat genetics and its wild relatives, are interconnected within a research framework aimed at improving the nutritional and qualitative traits of wheat. The exploration of the CslF6 gene and its role in β-glucan biosynthesis, alongside the characterization of qualitative traits such as protein content and yellow index, contributes to a deeper understanding of the genetic potential of wheat species, particularly those from wild genotypes such as Ae. caudata. The information obtained from this research offers new opportunities for the selection and development of more nutritious, sustainable, and consumer-oriented wheat varieties worldwide.