Genome-wide discovery of DNA variants in cucumber somaclonal lines

Abstract The emergence of somaclonal variability in in vitro cultures is undesirable during micropropagation, but this phenomenon may be a source of genetic variability sought by breeders. The main factors that affect the appearance of variability are known, but the exact mechanism has not yet been determined. In this paper, we used next-generation sequencing and comparative genomics to study changes in the genomes of cucumber lines resulting from in vitro regeneration and somaclonal mutation in comparison to a reference, the highly inbred B10 line. The total number of obtained polymorphisms differed between the three somaclonal lines S1, S2 and S3, with 8369, 7591 and 44510, respectively. Polymorphisms occurred most frequently in non-coding regions and were mainly SNPs. High-impact changes accounted for 1%–3% of all polymorphisms and most often caused an open reading frame shift. Functional analysis of genes affected by high impact variants showed that they were related to transport, biosynthetic processes, nucleotide-containing compounds and cellular protein modification processes. The obtained results indicated significant factors affecting somaclonal variability and the appearance of changes in the genome, and demonstrated a lack of dependence between phenotype and the number of genomic polymorphisms.