Abalone genomics reveals an ancient asymmetry axis and the multifunctionality of the mantle.

Abstract

Gastropod diversification represents one of the most spectacular evolutionary radiations, underpinned by a fundamentally asymmetric body plan and diverse pigmentation patterns. To understand the genetic underpinnings of these cardinal traits, we constructed a chromosome-level genome assembly for the rainbow abalone, <i>Haliotis iris</i>. Integrating comparative genomics, histoembryology, and molecular assays, we identify a conserved regulatory association between the long non-coding RNA <i>lncRNA1</i> and <i>pitx</i> that is associated with asymmetric mantle development. In <i>H. iris</i>, this association is supported by chromatin-contact evidence and exploratory data suggesting a possible miRNA-associated post-transcriptional component. Furthermore, we identify a <i>wnt-mitf-tyr</i> framework for melanogenesis and show that the mantle is the primary site of melanin synthesis. Concurrently, we identify mantle-enriched <i>prestin</i> genes that are vibration-responsive, consistent with a possible sensory specialization of the mantle. These findings provide molecular insight into asymmetry, pigmentation, and mantle multifunctionality in gastropods.