Abstract
Interspecific hybridization may lead to sterility and/or inviability through differential expression of genes and transposable elements (TEs). In Drosophila, studies have reported massive TE mobilization in hybrids from interspecific crosses of species presenting high divergence times. However, few studies have examined the consequences of TE mobilization upon hybridization in recently diverged species, such as Drosophila arizonae and D. mojavensis. We have sequenced transcriptomes of D. arizonae and the subspecies D. m. wrigleyi and their reciprocal hybrids, as well as piRNAs, to analyze the impact of genomic stress on TE regulation. Our results revealed that the differential expression in both gonadal tissues of parental species was similar. Globally, ovaries and testes showed few deregulated TEs compared with both parental lines. Analyses of small RNA data showed that in ovaries, the TE upregulation is likely due to divergence of copies inherited from parental genomes and lack of piRNAs mapping to them. Nevertheless, in testes, the divergent expression of genes associated with chromatin state and piRNA pathway potentially indicates that TE differential expression is related to the divergence of regulatory genes that play a role in modulating transcriptional and post-transcriptional mechanisms.
Highlights
Published: 18 December 2021Transposable elements (TEs) are repetitive DNA sequences that move from one place to another in the genome and between genomes
A total of 250 (83.5%) transposable elements (TEs) families were found expressed, of which 86.7% are common to D. arizonae and D. m. wrigleyi, 11.2% are exclusive to D. m. wrigleyi, and 2.1% are exclusive to D. arizonae
D. arizonae ovaries and testes compared with D. m. wrigleyi (X2 = 31.853, p = 1.663 × 10−8 ; X2 = 16.81; p = 4.132 × 10− 5 ) (Figure 1a,b)
Summary
Transposable elements (TEs) are repetitive DNA sequences that move from one place to another in the genome and between genomes. Because of their ability to mobilize, these elements play an important role in creating genetic variability and, in genome evolution and adaptation [1,2,3]. The disruption of genome stability following hybridization is attributed to the divergence of regulatory sequences and/or to the content of TEs [9]. In interspecific hybrids obtained from highly divergent parental species, massive TE expression and mobilization have been observed [7,9,17,18,19,20,21]
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