Transcriptome analyses of dark-induced bleaching octocorals and improvement in octocoral RNA extraction

Abstract

Abstract Octocorals, vital components of reef ecosystems, inhabit a wide range of marine environments across various climate zones, spanning from tropical shallows to frigid deep-sea regions. Certain octocoral species, notably Lobophytum and Sinularia, are particularly intriguing due to their production of diverse metabolites, warranting continuous investigation. Octocorals harboring symbiotic algae are prone to bleaching when subjected to stressors like elevated temperatures and intense sunlight. Interestingly, octocorals with greater tolerance to water turbidity may experience reduced light exposure, which can disrupt photosynthesis and result in bleaching. However, in comparison to stony coral (scleractinian), our knowledge of octocorals' physiological resilience under various stressors remains limited, and the genetic expression of octocorals has been relatively understudied. To address these gaps, our study focuses on comparing the transcriptomes of healthy octocorals and those induced to bleach by darkness, specifically focusing on Lobophytum hsiehi. Additionally, considering the challenges posed by the high fluid content and rich bioactive compounds within octocorals, we have devised a universal protocol for RNA extraction from six different octocoral genera. We believe that the findings of this study, along with the developed RNA extraction method, will serve as valuable references for future research, particularly in the realm of octocorals.