Abstract

Seeds are more than a primary input for the establishment of agronomic, horticultural and forestry crops since they are currently a delivery mechanism for breeding and biotechnological advances. In this regard, improving the content and the nutritional value of multiple compounds through plant breeding has become an essential goal on the seed enhancement. For example, studying the carotenoid biosynthetic pathway to increase the grain yellow pigment content (GYPC) and the nutritional value of grains of durum wheat, which is mainly used in the production of pasta, will considerably benefit the consumers and the industry. However, the key genetic constituents that regulate GYPC have been neither studied nor characterized in cultivars employed in Chile. In this project, the genetic diversity will be obtained from the Centro Internacional de Mejoramiento de Maíz y Trigo (CIMMYT) and the United States Department of Agriculture (USDA) that will be characterized and utilized in upcoming breeding programs, which is relevant if we consider the present objective of the Chilean authorities to position our country as a food power. In this context, the effects of phytoene synthase (PSY) on GYPC of nine cultivars utilized in Chile and of lycopene epsilon cyclase (LCYE) on the nutritional value of grains of durum wheat will be investigated. In parallel, the fine mapping of the 6A quantitative trait loci (QTL) will allow the identification of molecular markers associated to high GYPC that can be used in breeding programs to increase grain yellowness. Additionally, the PSY allelic variants and the 6A QTL will be introgressed into the Chilean cultivars by backcrossing and marker-assisted selection with the purpose to identify the genotypes with higher GYPC. To test the hypothesis of the association between the already identified PSY alleles related to high GYPC, PSY will be studied using Polymerase Chain Reaction (PCR) for gene amplification followed by sequencing based upon the existing allelic variants of PSY-A1 and PSY-B1 obtained from the literature. In this way, the superior PSY allelic variants associated with high GYPC will be identified and characterized. Regarding LCYE, Targeting-Induced Local Lesions IN Genomes (TILLING), a reverse-genetic strategy for the discovery and mapping of induced mutations will be used. This recently developed technique combines traditional mutagenesis with high-throughput discovery of single-nucleotide changes, which will presumably allow the identification of nutritionally-enhanced seeds with higher content of provitamin A through high-performance liquid chromatography (HPLC). Overall, the central objective of this project is to improve the content and the quality of the carotenoid pigments of grains of durum wheat as a superior approach to enhance the pasta quality in Chile. In addition, the novel findings of this project will contribute to a better scientific understanding of how PSY, the 6A QTL and LCYE affect this pathway, leading to different GYPC and nutritional value of the grains of durum wheat.