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

CHAVARRO MC; JACKSON SA; CHALUP L; BERTIOLI DJ; SAMOLUK SS; ROBLEDO G.; SEIJO JG

Córodoba

Conferencia; 9th International Conference of the Peanut Research Community- AAGB 2017; 2017

Itwas previously shown that changes in the repetitive genome fraction were aprimary driving force in genome differentiation between the A and B genomes ofsection Arachis. However, to fully understand the role of the repetitivesequences in the evolution of Arachisspecies, 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 genomeshotgun sequencing reads from A.glandulifera was generated. A total of 635Mbp of sequence data was used to perform a low-coveragegraph-based clustering approach implemented in the RepeatExplorer software. This analysis showed that about 72 % of the genome is composedof repetitive sequences. TheLTR-retroelements make up most of the repetitive DNA (57 %), particularly theTy3-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 thissatDNA showed that this sequence localized to most of the DAPI+ heterochromatic bands,suggesting that it is likely the major component of these chromosomal regions. Thiswork provides insights into the chromosome structure and repetitive compositionof A. glandulifera genome, and evidencethat satDNAs may have played a key role in the genome diversification of sectionArachis.