Genome-wide identification and characterization of SLEEPER, a transposon-derived gene family and their expression pattern in Brassica napus L.

Background: The transposons of the hAT superfamily are the most widespread transposons ever known. SLEEPER genes encode domesticated transposases from the hAT superfamily, which may have lost their transposable functions during long-term evolution and transformed into host proteins that regulate plant growth and development.

Results: This study identified 162 members of the SLEEPER gene family from Brassica napus. These members are widely distributed on 19 chromosomes, mainly in the Cn subgenome, and have promoters with various cis-acting elements related to hormone regulation, abiotic stress, and growth and development regulation. Most of the genes in this family contain similar conserved domains and motifs, and the closer the genes are distributed on evolutionary branches, the more similar their structures are. Transcriptome sequencing performed on tissues at different growth stages from B. napus line 3529 indicated that these genes had different expression patterns, and nearly half of the genes were not detectably expressed in all samples.

Conclusions: This study investigated the gene structure, expression patterns, evolutionary features, and gene localization of the SLEEPER family members to confirm the significance of these genes in the growth of B. napus, providing a reference for the study of transposon domestication and outstanding genetic resources for the genetic improvement of B. napus.