Evolutionary aspects of the plastomes of subfamily Opuntioideae (Cactaceae)

• Ano de defesa: 2021
• Autor(a) principal: Silva, Maria Carolina
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Biologia molecular; Sequenciamento de nucleotídeo; Plastídios; Marcadores moleculares; Edição de RNA; Rearranjo Gênico; Genômica; Mapeamento genômico; Filogenia; Genética Vegetal
• Link de acesso: https://locus.ufv.br//handle/123456789/28836; https://doi.org/10.47328/ufvbbt.2021.150

The plastid emerged through endosymbiosis. This organelle has a circular genome (plastome) of 100 to 220 kb with a quadripartite structure and harboring around 130 genes. The plastid genes are mainly involved in two processes, photosynthesis and gene expression. The non- propagation of plastid genes trough pollen, results at reduced evolutionary variation of these genes, favoring their use as molecular markers in phylogenetic studies at higher taxonomic ranks. On the other hand, there is a high variation in intergenic spaces and introns, which can be used in phylogenetic at lower taxonomic ranks and population genetic studies. Plastid genomics allow us to visualize the evolution of species through plastome rearrangements, gene divergence and degeneration, positive selection, and RNA editing sites. Therefore, the aim of this study was the sequencing of three plastomes of the subfamily Opuntioideae: Brasiliopuntia brasiliensis, Opuntia monacantha, and Opuntia ficus-indica. These species are widely cultivated and used for food, animal fodder, and ornamental purposes. Besides, they have pharmacological applications, as they present interesting bioactive compounds. Here, we characterize in detail the plastome structures, evolution of plastid genes, mapping of molecular markers, and phylogenetic relationships based on plastid sequences. Structurally, Opuntioideae shows unique rearrangements within Cactaceae, such as expansion of the inverted regions. Molecular evolution analyses of the protein-coding genes show a high divergence of genes involved in essential plastid functions. Furthermore, more than half of these plastid genes bear signatures of positive selection. Several shared RNA editing sites were predicted to occur in the plastid genes of the three species in study. Besides, hundreds of molecular markers were mapped in the plastomes sequenced here, which are informative sequences useful to improve taxonomic classifications and conservation strategies of these species. Moreover, the phylogeny based on concatenated genes resulted in a well-supported tree; with Opuntioideae forming a monophyletic clade that is a sister group of Cactoideae. Finally, this study shades light on the evolutionary patterns of the subfamily Opuntioideae (Cactaceae), and contributes with plenty of useful data to be explored and applied to access and understand the genetic diversity of these Opuntioideae species and trace adequate strategies of rational use and conservation. Keywords: Plastome evolution. Gene divergence. Rearrangements. Positive selection. RNA editing. Molecular markers.