Sequence Evolution, Abundance, and Chromosomal Distribution of Ty1-copia Retrotransposons in the Saccharum spontaneum Genome

Saccharum spontaneum is a wild germplasm resource of the genus Saccharum that has many valuable traits. Ty1-copia retrotransposons constitute a large proportion of plant genomes and affect genome sequence organization and evolution. This study aims to analyze the sequence heterogeneity, phylogenetic diversity, copy number, and chromosomal dispersion patterns of Ty1-copia retrotransposons in S. spontaneum. A total of 44 Ty1-copia reverse transcriptase subclones isolated from S. spontaneum showed a range of heterogeneity, and all sequences were A-T rich, averaging approximately 54.59%. Phylogenetic analysis divided the 44 reverse transcriptase sequences into 5 distinct lineages (Retrofit/Ale, Sire/Maximus, Bianca, Tork/TAR, and Ty1-copia like). Dot-blot hybridization revealed that Ty1-copia retrotransposons consisted of a significant component of approximately 38,900 copies and 16,300 copies per genome in the accessions YN82-114 (2n = 10x = 80) and AP85-441 (2n = 4x = 32), respectively. The results of a local blast analysis showed that there are 15,069 Ty1-copia retrotransposon copies in the genome of AP85-441, of which the Retrofit/Ale lineage had the highest copy number, followed by the Tork/TAR, Sire/Maximus, and Bianca lineages. Furthermore, both FISH and the local blast analysis with AP85-441 genomic data demonstrated that the Ty1-copia retrotransposons were unevenly distributed throughout the chromosomes. Taken together, this study provides insights into the role of Ty1-copia retrotransposons in the evolution and organization of the S. spontaneum genome.

Bioinformatic identification of Ty1/Copia-like transposable elements in Deschampsia antarctica E. Desv.

Aim. Identification of Ty1/Copia-like transposable elements in Deschampsia antarctica E Desv. in silico. Methods. Bioinformatic analysis of sequence read archives of D. antarctica genome and transcriptome contained in the GenBank database was conducted. The search was carried out using the rice Ty1/Copia TE Tos 17 as a reference sequence. Results. The search revealed the sequences of Ty1/Copia retrotransposons in the D. antarctica genome to show a high level of identity (up to 75% in the homologous regions) to Tos 17. The uneven distribution of the found reads along the reference sequence indicates the existence of a group of the sequences in the genome to contain elements typical of the family and have varying degrees of identity to Tos 17, with more conservative ones being represented in correspondingly greater numbers among the found reads. The presence of the reads identical to Tos 17 in transcriptome indicates that the TE sequences identified in genome have a certain background level of transcriptional activity. Conclusions. Transcriptionally active Ty1/Copia-like transposable elements were identified in silico in D. antarctica genome using methods of bioinformatics. The sequences found can be used to construct primers for PCR and to analyze the activity of the TE of this family in D. antarctica in further studies. Keywords: bioinformatic analysis, Deschampsia antarctica E Desv., transposable elements, Ty1/Copia.