Synthesis of transcriptomic studies reveals a core response to heat stress in abalone (genus Haliotis)

As climate change causes marine heat waves to become more intense and frequent, marine species increasingly suffer from heat stress. This stress can result in reduced growth, disrupted breeding cycles, vulnerability to diseases and pathogens, and increased mortality rates. Abalone (genus Haliotis) are an ecologically significant group of marine gastropods and are among the most highly valued seafood products. However, heat stress events have had devastating impacts on both farmed and wild populations. Members of this genus are among the most susceptible marine species to climate change impacts, with over 40% of all abalone species listed as threatened with extinction. This has motivated researchers to explore the genetics linked to heat stress in abalone. A substantial portion of publicly available studies has employed transcriptomic approaches to investigate abalone genetic response to heat stress. However, to date, no meta-analysis has been conducted to determine the common response to heat stress (i.e. the core response) across the genus. This study uses a standardized bioinformatic pipeline to reanalyze and compare publicly available RNA-seq datasets from different heat stress studies on abalone.

Nine publicly available RNA-seq datasets from nine different heat-stress studies on abalone from seven different abalone species and three hybrids were included in the meta-analysis. We identified a core set of 74 differentially expressed genes (DEGs) in response to heat stress in at least seven out of nine studies. This core set of DEGs mainly included genes associated with alternative splicing, heat shock proteins (HSPs), Ubiquitin-Proteasome System (UPS), and other protein folding and protein processing pathways.

The detection of a consistent set of genes that respond to heat stress across various studies, despite differences in experimental design (e.g. stress intensity, species studied-geographical distribution, preferred temperature range, etc.), strengthens our proposal that these genes are key elements of the heat stress response in abalone. The identification of the core response to heat stress in abalone lays an important foundation for future research. Ultimately, this study will aid conservation efforts and aquaculture through the identification of resilient populations, genetic-based breeding programs, possible manipulations such as early exposure to stress, gene editing and the use of immunostimulants to enhance thermal tolerance.