Fração do DNA repetitivo na batata silvestre Solanum calvescens Bitter e espécies relacionadas

Abstract

The search for alleles of interest in wild potato species is a promising strategy in improvement programs targeting superior cultivars, especially with regard to biotic and abiotic stresses. The triploid native species Solaunum calvescens (2n=3x=36) is one of the potential species for use in potato improvement, but it has no conclusive taxonomic status. Not considered as a species by some authors, being sometimes defined as a cytotype of Solanum chacoense (2n=2x=24), sometimes as close to Solanum commersonii subsp. malmeanum, or even a hybrid between these two species. Crossing S. calvescens with cultivated potato (Solanum tuberosum, 2n=4x=48) produces viable hybrids for selection in a breeding program. Due to this potential, the taxonomic definition and knowledge of the origin of this species is relevant. Therefore, this study aimed to characterize the repetitive fraction of the DNA of this native species, comparatively with its related species, in order to gather new genomic information to collaborate with the elucidation of the relationship between them. For S. calvescens, low pass sequencing was performed on the Illumina platform and genome size was determined by flow cytometry. For the species S. chacoense, S. commersonii, S. malmeanum and S. etuberosum, data published and made available by the authors were used. The sequences were analyzed in the Repeat Explorer platform, in which the steps of pre-processing, grouping and identification of repetitive elements were performed. Geneious software was used for satellite alignment, identification and quantification. The genome size of S. calvescens proved to be larger compared to related species. The amount of repetitive DNA present in the species ranged from 38.37% of the genome in S. calvescens to 45.37% in S. chacoense, with a predominance of the LTR group and Ty3/gypsy superfamily in all species. All mapped satellites had less than 50% identity, grouping them only at the superfamily level. The species S. chacoense presented a species-specific satellite, SchacSat10. Regarding genome size and repetitive fraction characteristics, S. calvescens differs from other species.