Análises evolutivas em Spondias L.: uma abordagem genômica do gênero.

Abstract

The genus Spondias is a group of fruit trees of the family Anacardiaceae that includes species of economic importance, with distribution in the neotropical regions. Studies of genomic characterization in the genus have the potential to provide important information for the understanding of the origin and evolution of the species. In this perspective, the objective of this study was to sequence the mitogenomas, to evaluate the DNA content and to characterize the repetitive fraction of the genome of species of the genus Spondias, in order to describe the composition of the repetitive sequences in the genomes and to establish evolutionary relationships with foligenia in the genus Spondias. For this, extraction of S. tuberosa, S. mombim, S. bahiensis, Spondias sp. and Spondias dulcis and prepared single-end and paired-end reads libraries and performed bioinformatics analyzes on computational software for assembly of mitochondrial genomes and characterization of the repetitive fraction of genomes, as well as quantification of genomic DNA content using flow cytometry. The mitogenomes presented 779,106 bp and 674,156 bp, for S. tuberosa and S. mombin, exhibiting a total of 74 genes and 68 genes, respectively, with structure with many rearrangements mediated by the presence of repetitive DNA and high incorporation of chloroplast DNA. Analysis of the DNA content and the repetitive fraction of the genome demonstrated that the sizes of the Spondias genomes analyzed ranged from 460 to 530 Mb and phylogenetic analysis revealed a tendency to increase the size of the genome in derived species. The analyzes in the Repeat Explorer resulted in the identification and characterization of the repetitive DNA, making up approximately 15.11% in S. tuberosa, 22.41% in S. mombim, 18.21% in Spondias sp, 14.12% S. bahiensis and 29.65% in S.dulcis. For SatDNA, two main satellites distributed in all species were observed, with SatSpo1 being highly diversified in the genus. In addition, for S. tuberosa a satellite was detected in the intergenic spacer of rDNA. In situ genomic hybridization of satDNA (SatSpo1 and SatSpo2) evidenced the low repetitive DNA diversification, the presence of GC-rich satellites that are likely to be distributed in heterochromatin regions. From this, it is concluded that the genus Spondias has a recent diversification to repetitive DNA, with similar distribution of TEs and families of satDNA among the species.