The repetitive landscape of Arachis glandulifera (Leguminosae) investigated by low-depth Illumina sequencing

SAMOLUK, SEBASTIÁN; CHALUP, LAURA; CHAVARRO, C; ROBLEDO, GERMÁN; BERTIOLI, DAVID; JACKSON SCOT; SEIJO, GUILLERMO

Cordoba

Conferencia; Nineth Internatinal Conference of the Peanut Research Community. Community - Advances in Arachis through Genomics & Biotechnology; 2017

It was previously shown that changes in the repetitive genome fraction were a primary driving force in genome differentiation between the A and B genomes of section Arachis. However, to fully understand the role of the repetitive sequences in the evolution of Arachis species, additional data including species having different genomes are needed. Here we analyze the repetitive component of A. glandulifera, which is the only wild diploid species (2n =2x = 20, C-value: 1315 Mbp) of the D genome. For this purpose, low-coverage Illumina whole genome shotgun sequencing reads from A. glandulifera was generated. A total of 635 Mbp of sequence data was used to perform a low-coverage graph-based clustering approach implemented in the RepeatExplorer software. This analysis showed that about 72 % of the genome is composed of repetitive sequences. The LTR-retroelements make up most of the repetitive DNA (57 %), particularly the Ty3-gypsy superfamily, as observed in the A and B genomes. Tandem repeats (microsatellites, satellites and rDNA) were the second most abundant (8 %) repetitive sequences. Among the satDNAs, the CL8 was the most represented. The chromosome distribution by FISH of this satDNA showed that this sequence localized to most of the DAPI+ heterochromatic bands, suggesting that it is likely the major component of these chromosomal regions. This work provides insights into the chromosome structure and repetitive composition of A. glandulifera genome, and evidence that satDNAs may have played a key role in the genome diversification of section Arachis.