GENETIC DISSECTION OF MATURITY DATE IN PEACH AND APRICOT REVEAL A ROLE FOR CONSERVED GENE NETWORKS

Peach (Prunus persica L. Batsch) and apricot (Prunus armeniaca L.) are crop tree species with a moderate economic relevance and widely cultivated in temperate regions due to the highly appreciated fruits. Due to its characteristics, peach became a model crop, a relatively small genome (about 256 Mb), diploidy (2n = 2x = 16) and low heterozygosity. Conversely apricot shows high levels of heterozygosity and consistent structural variations, limiting a direct knowledge transfer from peach. Maturity Date (MD) is a complex trait, influenced by multiple factors, both environmental and genetical, being of notewhorthy importance and impact in the orchard management activities. Nevertheless MD is characterized by a high variability, having cultivated varieties classified from very early to ultra-late ripening. Dissection of the genetic control of MD have been approached by numerous studies. Usage of QTL mapping led to the identification of stable loci, both in peach, with qMD4.1 and in apricot that yet show several limitation, such as the scarcity of large segregating populations and high heterozygosity, hindering clear-cut identification of candidate genes. More than ever implementation of several different approaches, fine mapping, comparative genomics, new sequencing technologies are required to be able to investigate the underlying genetic control of MD in Prunus. Chapter 2 shows the integration of multiple approaches to identify major QTLs in the segregating population ‘Dulcebo66 x Pulchra’, through recombinant individual qMD4.1 position have been refined, then combined Illumina short-read and Oxford Nanopore long-read sequences have been used to characterize the structural variations of the region. In chapter 3 QTls associated to MD have been identified in the segregating population ‘BO96621030 x Harostar’. By combining different approaches, such as high-density genotyping, QTL mapping, extensive phenotyping of a numerous population, fine mapping, and whole genome resequencing, the QTL have been reduced to an interval containing six annotated genes.