Genetic parameters estimation and QTL mapping in Sesamum indicum L.

Brazil has experienced an exponential increase in sesame production in recent years. Still, farmers face many challenges in cropping sesame, such as the low number of available cultivars adapted to mechanized harvesting. In Brazil, few advances have been made in crop breeding. There is still a lack of germplasm characterization, and genetic breeding work is being developed to increase productivity and adapt to mechanized harvesting. The first chapter of this work presents a study of estimates of sesame genetic parameters in different environments and the characterization of the diversity available. A total of 28 sesame genotypes were phenotypically evaluated in three environments and genotyped with microsatellite and SNP markers. After statistical analysis, significant genetic variability was observed in the genotypes evaluated, which can be explored in crossings in the breeding program. Most of the phenotypic traits evaluated were highly influenced by the environment, presenting genotype x environment interaction and highlighting the complexity of improvement for this crop. In the second chapter, a QTL mapping study was carried out using SNP markers to identify genomic regions associated with traits of interest in sesame breeding. Two F2 populations (SD and SJ) were developed by hybridization, consisting of 98 and 160 genotypes, respectively. Both populations were genotyped by SNP markers and phenotyped in a greenhouse. After statistical analyses, QTL markers were found for 15 of the 17 phenotypic traits evaluated. QTL markers associated with important agronomic traits in sesame were found, such as productivity-related traits, placental adherence, and growth habit. Keywords: Sesame breeding; Selection index; Associative mapping; GxE interaction.