Comparative transcriptome sequencing of two shell colour variants of Haliotis discus hannai identifying genes involved in shell formation and photosensitivity

Shell colour variation in Haliotis discus hannai is a complex trait influenced by genetic, physiological, and environmental factors. This study investigates the molecular mechanisms underlying shell colour formation, with a focus on the roles of biomineralisation, photosensitivity, and stress resistance. Using transcriptome analysis and microstructural observations, we compared red-shelled (RS) and green-shelled (GS) variants to identify key genes and pathways associated with shell colour. The results reveal that GS variants exhibit higher expression of visual protein genes (e.g., RHO-opnGq), which are linked to light sensitivity and pigment synthesis. Additionally, RS variants show upregulated chitin biosynthesis genes (e.g., CHs-IA), potentially influencing shell structure and pigmentation. These findings suggest that these genes play a critical role in regulating pigment deposition and shell colour formation, while biomineralisation genes contribute to shell integrity. This study provides new insights into the genetic basis of shell colour variation and its ecological significance, offering valuable information for selective breeding programs.