Transcriptomic basis of sex loss in the pea aphid

M D Huguet (1) , Stéphanie Robin (1, 2) , Sylvie Hudaverdian (1) , Sylvie Tanguy (1) , Nathalie Prunier-Leterme (1) , Romuald Cloteau (1) , Sylvain Baulande (3) , Patricia Legoix-Né (3) , Fabrice Legeai (1, 4) , Jean-Christophe Simon (1) , Julie Jaquiéry (1) , Denis Tagu (1) , Gaël Le Trionnaire (1)

1 IGEPP - Institut de Génétique, Environnement et Protection des Plantes
2 Plateforme Génomique Santé Biogenouest®
3 Institut Curie [Paris]
4 GenScale - Scalable, Optimized and Parallel Algorithms for Genomics

BACKGROUND: Transitions from sexual to asexual reproduction are common in eukaryotes, but the underlying mechanisms remain poorly known. The pea aphid-Acyrthosiphon pisum-exhibits reproductive polymorphism, with cyclical parthenogenetic and obligate parthenogenetic lineages, offering an opportunity to decipher the genetic basis of sex loss. Previous work on this species identified a single 840 kb region controlling reproductive polymorphism and carrying 32 genes. With the aim of identifying the gene(s) responsible for sex loss and the resulting consequences on the genetic programs controlling sexual or asexual embryogenesis, we compared the transcriptomic response to photoperiod shortening-the main sex-inducing cue-of a sexual and an obligate asexual lineage of the pea aphid, focusing on heads (where the photoperiodic cue is detected) and embryos (the final target of the cue). RESULTS: Our analyses revealed that four genes (one expressed in the head, and three in the embryos) of the region responded differently to photoperiod in the two lineages. We also found that the downstream genetic programs expressed during embryonic development of a future sexual female encompass ∼1600 genes, among which miRNAs, piRNAs and histone modification pathways are overrepresented. These genes mainly co-localize in two genomic regions enriched in transposable elements (TEs). CONCLUSIONS: Our results suggest that the causal polymorphism(s) in the 840 kb region somehow impair downstream epigenetic and post-transcriptional regulations in obligate asexual lineages, thereby sustaining asexual reproduction.

Mots clés: Asexuality; Cyclical and obligate parthenogenesis; Gene expression; Insects; Reproductive polymorphism

Domaines: Sciences du Vivant [q-bio]

M D Huguet, Stéphanie Robin, Sylvie Hudaverdian, Sylvie Tanguy, Nathalie Prunier-Leterme, et al.. Transcriptomic basis of sex loss in the pea aphid. BMC Genomics, 2024, Bmc Genomics, 25 (1), pp.202. ⟨10.1186/s12864-023-09776-6⟩. ⟨hal-04484084⟩