Genes possibly related to symbiosis in early life stages of Acropora tenuis inoculated with Symbiodinium microadriaticum

Abstract

Due to the ecological importance of mutualism between reef-building corals and symbiotic algae (Family Symbiodiniaceae), various transcriptomic studies on coral-algal symbiosis have been performed; however, molecular mechanisms, especially genes essential to initiate and maintain these symbioses remain unknown. We investigated transcriptomic responses of Acropora tenuis to inoculation with the native algal symbiont, Symbiodinium microadriaticum, during early life stages, and identified possible symbiosis-related genes. Genes involved in immune regulation, protection against oxidative stress, and metabolic interactions between partners are particularly important for symbiosis during Acropora early life stages. In addition, molecular phylogenetic analysis revealed that some possible symbiosis-related genes originated by gene duplication in the Acropora lineage, suggesting that gene duplication may have been the driving force to establish stable mutualism in Acropora, and that symbiotic molecular mechanisms may vary among coral lineages.

Genomic Data Reveal Diverse Biological Characteristics of Scleractinian Corals and Promote Effective Coral Reef Conservation

“…The gene repertoire specifically involved in symbiosis with native symbionts suggests that when planula larvae harbor native symbionts, they slow metabolic activities and prepare to acquire photosynthetic products from algal symbionts via transporter genes. Since symbiosis-related genes are continuously expressed or suppressed when corals acquire algal symbionts, algal inoculation experiments using primary polyps, the next developmental stage of planula larvae, were performed to correctly distinguish between genes associated with symbiosis and those involved in development ( Yoshioka et al 2023 ). Consequently, 15 genes that are differentially expressed in response to native symbiont infection have been identified as symbiosis-related genes in Acropora early life stages.…”

“…Deduced functions of symbiosis-related genes include transporters for metabolic interactions, protection against oxidative stress, immune system, and the Notch-related signaling pathway ( Fig. 2 , Yoshioka et al 2023 ). Interestingly, although some symbiosis-related genes have only a single copy in cnidarians ( Fig.…”

“… The diverse evolutionary background of possible symbiosis-related coral genes, reflects various mechanisms of molecular symbiosis among coral lineages. a) Possible symbiosis-related genes in early life stages of Acropora tenuis ( Yoshioka et al 2023 ). b) Hypothetical functions of symbiosis-related genes in early life stages of Acropora tenuis during symbiosis with the native symbiont, Symbiodinium microadriaticum .…”

“…d) An Acropora -specific, duplicated, symbiosis-related gene, Solute carrier family 2, facilitated glucose transporter member 8 ( SLC2A8-2 ). Detailed molecular phylogenetic trees are available in Yoshioka et al (2023) .…”