Genoma cloroplastidial de Serjania erecta Raldk: variação no número de genes e análise de seleção de genes de plastomas da família Sapindaceae

Abstract

Serjania erecta from the Sapindaceae family is a plant with medicinal properties. Studies indicate potential for use in the treatment of Alzheimer's disease, gastric diseases and anti-inflammatory use. Although, little is known about its genetic and evolutionary aspects. The goal of this study was to assemble the chloroplast genome of S. erecta, and use it in a comparative analysis with other plastomas of the Sapindaceae family. For this, we sequenced a single specimen of S. erecta from Araxá (MG - Brasil) using Illumina Miseq. The chloroplast genome was assembled using NOVOPlasty v3.2 and annotated using the CHLOROBOX platform. For comparative analysis was used eleven chloroplast genomes from different Sapindaceae family species (Acer buergerianum, Aesculus wangii, Dimocarpus longan, Dipteronia dyeriana, Dodonaea v iscosa, Eurycorymbus cavaleriei, Koelreuteria paniculata, Litchi chinensis, Pometia tomentosa, Sapindus mukorossi, Xanthoceras sorbifolium). The chloroplast genome of S. erecta has a size of 159,297 bp with 132 genes, including 87 are protein-coding genes, 37 are tRNAs and 8 rRNAs. Among twelve chloroplast genomes avalieded, S. erecta has the lowest amount of complex repeats and microsatellites. The structure and order of genes in chloroplast genomes of the order Sapindales was extremely conserved. The variation in numbers of genes was from the 132 genes to 128 genes in the Sapindaceae family. We suggest that three factors cause variation in the number of genes in the family: (1) Inverted repeat region (IR) expansion events cause the duplication of the rpl22, rps3 and rps19 genes; (2) the pseudogenization of the rps2 gene; (3) variation in the number of genes encoding tRNAS. The phylogenetic tree had well supported nodes within Sapindaceae and Serjania formed a clade with Sapindus, Litchi, Dimocarpus, and Pometia genera. Only two genomic regions (ycf1 and ndhF) showed high nucleotide diversity and no one gene is under positive selection (ka/ks > 1). The results obtained in this study provide the assembly and annotation of the chloroplast genome of S. erecta, the first annotation of a species of the genus. It also provides an idea of how chloroplast genomes evolved in the Sapindaceae family.