Physical mapping and evolution of banana genome (Musa spp.)

Bananas (Musa spp., family Musaceae) are one of the top export commodities and an essential nutrition source for millions of people, especially in developing countries of tropical and subtropical regions. Despite the unquestionable importance of this crop, there is a lack of knowledge about the genetic diversity, phylogenetic relationships and the structure, organization and evolution of banana genome. This study employed several molecular approaches with the aim to contribute to the characterization of the genetic diversity and evolution of species belonging to the family Musaceae. Cytogenetic mapping of specific sequences on mitotic chromosomes of bananas was used to shed more light on the structure and organization of banana genome. In the first part of this thesis, analysis of the ITS region of nrDNA was used to study the phylogenetic relationships within the family Musaceae. The study provides a plausible picture of the evolution of Musaceae species which can be further utilized in improving the classification within the genus. The second part of the work was aimed at molecular analysis and cytogenetic mapping of two main banana DNA satellites. Their genomic organization and molecular diversity was estimated in a set of nineteen Musa accessions. A high potential of these satellites as cytogenetic markers was shown. Their use as probes for FISH significantly increases the number of chromosomes which can be identified in Musa. In the third part of this thesis, genetic diversity of a set of wild Musa species was analysed. The study provides a novel data on nuclear genome size and genomic distribution of rRNA genes in banana and increases the knowledge about the genome structure of wild Musa species. For molecular characterization of studied accessions, SSR genotyping and analysis of the ITS region were used confirming their usefulness for assessing the genetic diversity and evolutionary relationships among banana species.