Effects of thermal priming on the Saccharina latissima transcriptomic response to heat stress
Authors
Anne M. L. Nilsen (presenting author) [1]
Niko Steiner [2]
Inka Bartsch [2]
J. Mark Cock [3]
Alexander O. Jueterbock [1]
Keywords
Kelp; Stress memory; Thermal tolerance; Transcriptomics; Saccharina latissima; Thermal priming
Abstract
Saccharina latissima (sugar kelp) is a brown macroalga forming extensive kelp forests along North Atlantic coasts. These habitats are key components of coastal ecosystems, contributing substantially to primary production, nutrient cycling, and biodiversity support. In addition, S. latissima is the most common cultivated kelp species in European aquaculture, offering a sustainable source of food, feed, and biomaterials without fertilizer and freshwater demands. However, both natural and cultivated populations are increasingly exposed to elevated sea temperatures and marine heatwaves, posing significant challenges for resilience and sustainable production. Kelp species have a diplohaplontic life cycle, alternating between haploid gametophytes and diploid sporophytes. This alternation enables manipulation of gametophyte stages and testing of transgenerational effects in the resulting sporophytes. Thermal priming, originally described in terrestrial plants, exposes early life stages to moderate heat stress to induce a physiological and molecular memory that enhances stress tolerance at later life stages. We applied this concept to S. latissima by exposing gametophytes to moderate heat (20 °C, 3 weeks) before sporophyte induction, while keeping naïve controls at 10°C. Sporophytes grown at 10°C, derived from primed and naïve gametophytes, were subsequently exposed to short-term heat stress (21.5 °C for 48 h) and allowed to recover at 10°C for 72h, during which we assessed transcriptomic responses and photosynthetic performance. Primed sporophytes mounted a stronger transcriptional response to heat stress during the exposure. In contrast, naïve sporophytes displayed delayed and extensive transcriptional downregulation during recovery. These findings indicate that defense mechanisms initiated in the gametophyte stage can be reactivated in the derived sporophyte stage, supporting the view that thermal priming induces a transgenerational stress memory in S. latissima.
Funding
Norwegian Research Council, KELPRIME project (project no. 700933)