The fate of duplicate genes in plants

• Ano de defesa: 2016
• Autor(a) principal: Silva, Hugo Rody Vianna
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Evolução molecular; Genética vegetal; Poliploidia; Biologia Molecular
• Link de acesso: http://www.locus.ufv.br/handle/123456789/7804

Plants are paleopolyploid organisms that survived the deleterious process of genome duplication. After duplication, copies of the same gene (paralogs) evolve in different ways due to the relaxation of purifying selection, making the duplicated genes the greatest source of evolutionary diversification. However, not all categories of genes are retained in the genomes, or lost, randomly. Several evolutionary models have been proposed to explain the evolutionary fate and biased retention of duplicate genes, to thereby better understand polyploidy. However, the applicability of these models has been ill defined. We used approaches of comparative genomics and molecular phylogeny to investigate the fate of duplicated genes in plants. Initially, we inferred about the ancestry of two small families of duplicated genes — methionine synthase and raffinose oligosaccharides — in the genomes of nine species of plants to then characterize the evolutionary forces that have shaped the evolutionary fate of paralogs, using resequencing data from 31 soybean genomes. Later, we used genomic data from 25 taxonomically different plant species to associate mechanisms of duplication, functional gene category and age of duplication to the biased retention of duplicate genes. In each of the two gene families, paralog evolved in different ways due to the relaxation of purifying selection, which allowed random mutations with adaptive value be fixed by positive selection. However, purifying selection seems to be more restrictive in at least one of paralogs of each gene family, preserving the ancestral function. Both the age and the mechanism of duplication contributed to variation in duplicate genes retention patterns in the 25 target genomes in this study. The fate and retention of duplicate genes in the genomes is apparently shaped by peculiarities inherent to each polyploid organism.