Biology subjects

Procaccini, G.

Publications and source records attributed to Procaccini, G..

5 recordsLinked to original sources

bioRxiv2026

Gene Expression Landscapes Driving Early Life Stages of the Keystone Seagrass Posidonia oceanica

Seagrasses are marine angiosperms forming extensive underwater meadows that provide habitat, stabilize sediments, store carbon, and protect coastlines. Posidonia oceanica is the endemic foundation seagrass species of the Mediterranean, yet its meadows are rapidly declining. Despite its ecological importance, the molecular basis of P. oceanica development remains poorly understood. Here, we analyzed gene expression in roots, leaves, and seeds across four developmental stages, revealing strong tissue-specific patterns and temporally regulated expression dynamics. Leaves exhibited active regulation of photosynthesis-related processes, while roots were enriched in pathways linked to carbohydrate metabolism and cell wall biogenesis, supporting primary root growth and establishment. Seeds retained metabolic activity, with glycolytic enzymes indicating readiness for germination. Temporal analyses identified a major transcriptional shift, with distinct gene sets sequentially activated during early establishment and late maturation across tissues. Weighted Gene Co-expression Network Analysis identified modules strongly associated with specific tissues and developmental transitions, highlighting key hub genes involved in photosynthesis, metabolism, cell wall remodeling, and protein synthesis. Together, these results reveal complex, temporally coordinated regulatory networks underlying P. oceanica development O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=164 SRC="FIGDIR/small/711526v1_ufig1.gif" ALT="Figure 1"> View larger version (83K): org.highwire.dtl.DTLVardef@d5b81forg.highwire.dtl.DTLVardef@12b01ceorg.highwire.dtl.DTLVardef@838d6borg.highwire.dtl.DTLVardef@b99b40_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightGene expression analyses reveal tissue-specific and temporally regulated networks driving Posidonia oceanica development, identifying key pathways and hub genes coordinating early establishment and late maturation across roots, leaves, and seeds.

plant biology↗

bioRxiv2025

Crossing thermal limits: functional collapse of the surfgrass Phyllospadix scouleri under extreme marine heatwaves

Marine heatwaves (MHWs) are intensifying under climate change, yet the physiological limits that constrain seagrass resilience remain poorly defined. We experimentally tested the responses of the surfgrass Phyllospadix scouleri, a foundation species of the Northeast Pacific coast, to simulated MHWs of contrasting intensity. In a 27-day mesocosm experiment, plants were exposed to fluctuating temperatures representing a severe MHW (23.5 {+/-} 1.5 {degrees}C) and an extreme MHW (26.5 {+/-} 1.5 {degrees}C), while photosynthetic performance, respiration, nitrogen metabolism, oxidative stress, and growth were monitored during and after warming. Phyllospadix scouleri maintained photosynthetic capacity and carbon balance under severe warming but exhibited pronounced physiological disruption at extreme temperatures, including sustained photoinhibition, reduced nitrate assimilation, elevated respiration, and negative daily productivity. These effects persisted after heat stress, leading to reduced growth and indicating incomplete recovery. Multivariate analyses revealed a distinct transition from tolerance to functional breakdown near 26.5 {degrees}C, suggesting a physiological tipping point only 5-6 {degrees}C above current summer maxima in the area of the studied population. Our findings demonstrate that intensifying MHWs may rapidly erode the thermal safety margin of temperate seagrasses, pushing foundational coastal ecosystems toward metabolic instability and potential regime shifts under continued ocean warming. HighlightExtreme marine heatwave disrupts photosynthesis, nitrogen metabolism, and carbon balance in the seagrass Phyllospadix scouleri, suggesting a narrow thermal safety margin in the face of ocean warming.

plant biology↗

bioRxiv2025

Transcriptome responses of two Halophila stipulacea seagrass populations from pristine and impacted habitats, to single and combined thermal and excess nutrient stressors, reveal local adaptive features and core stress-response genes

In their natural habitats, seagrasses face multiple abiotic stressors, which can often occur simultaneously. However, most studies investigating the effects of environmental stressors on seagrasses have focused on growth and physiological responses to single stressors. Here, we examined the transcriptome responses of the tropical seagrass Halophila stipulacea collected from a northern Gulf of Aqaba pristine site (South Beach - SB) and an anthropogenically-impacted site (Tur Yam - TY), grown in a mesocosm, and exposed to ecologically-relevant, single and combined, thermal and excess nutrient stressors. The combined thermal and nutrient stressor elicited greater transcriptome reprogramming than the single stressors in both populations and induced the expression of a combination-specific set of genes involved in abiotic and biotic stress responses. Furthermore, thermal stress exerted a more dominant influence than excess nutrient stress upon the transcriptome response to the combined stress. Transcriptomes of plants from the impacted TY site displayed reduced plasticity, the presence of genes exhibiting a "stress-ready" mode of expression under all stresses, and increased resilience (recovery to control transcriptomes). We also identified core stress-response genes that could be leveraged as early indicators of stress in the field. Overall, our data suggest that environmental conditions in seagrass habitats can drive local molecular adaptation, and that the response of seagrasses to combined stressors associated with climate change and coastal anthropogenic stressors cannot be predicted from the response to single stressors.

plant biology↗

bioRxiv2023

Seagrass genomes reveal a hexaploid ancestry facilitating adaptation to the marine environment

Seagrasses comprise the only submerged marine angiosperms, a feat of adaptation from three independent freshwater lineages within the Alismatales. These three parallel lineages offer the unique opportunity to study convergent versus lineage-specific adaptation to a fully marine lifestyle. Here, we present chromosome-level genome assemblies from a representative species of each of the seagrass lineages - Posidonia oceanica (Posidoniaceae), Cymodocea nodosa (Cymodoceaceae), and Thalassia testudinum (Hydrocharitaceae) - along with an improved assembly for Zostera marina (Zosteraceae). We also include a draft genome of Potamogeton acutifolius, a representative of Potamogetonaceae, the freshwater sister lineage to the Zosteraceae. Genome analysis reveals that all seagrasses share an ancient whole genome triplication (WGT) event, dating to the early evolution of the Alismatales. An additional whole genome duplication (WGD) event was uncovered for C. nodosa and P. acutifolius. Dating of ancient WGDs and more recent bursts of transposable elements correlate well with major geological and recent climatic events, supporting their role as rapid generators of genetic variation. Comparative analysis of selected gene families suggests that the transition from the submerged-freshwater to submerged-marine environment did not require revolutionary changes. Major gene losses related to, e.g., stomata, volatiles, defense, and lignification, are likely a consequence of the submerged lifestyle rather than the cause ( use it or lose it). Likewise, genes, often retained from the WGD and WGT, were co-opted for functions requiring the alignment of many small adaptations ( tweaking), e.g., osmoregulation, salinity, light capture, carbon acquisition, and temperature. Our ability to manage and conserve seagrass ecosystems depends on our understanding of the fundamental processes underpinning their resilience. These new genomes will accelerate functional studies and are expected to contribute to transformative solutions -- as continuing worldwide losses of the savannas of the sea are of major concern in times of climate change and loss of biodiversity.

evolutionary biology↗

bioRxiv2019

Seagrass excretes sugars to their rhizosphere making them the sweet spots in the sea

Seagrasses are one of the most efficient sinks of carbon dioxide on Earth1: They bury carbon 35 times faster than tropical rainforests on a per unit area basis2. While we know that carbon sequestration in terrestrial plants is intimately linked to the microorganisms living in their soils3-6, the interactions of seagrasses with their rhizospheres are poorly understood. We show that three seagrass species from two oceans excrete simple sugars, mainly sucrose, into their rhizosphere that accumulate to over 200 {micro}M. Such high concentrations are at least 80 times higher than previously observed in the ocean, and surprising, as sugars are quickly consumed by microorganisms. In situ analyses and incubation experiments indicated that phenolic compounds from the seagrass inhibited microbial consumption of sucrose. Metagenomic and metatranscriptomic analyses of the microbial communities in the seagrass rhizosphere revealed that many members had the genes for degrading sucrose, but these were only expressed by a few specialists that also expressed genes for degrading phenolics. Our results explain why sucrose accumulates under seagrass meadows, where it comprises as much as 40% of the dissolved organic carbon. Destruction of extant seagrass canopies would allow sediment microorganisms to consume the tremendous deposits of sucrose buried underneath their meadows, thereby releasing large amounts of CO2 into the oceans and atmosphere.

microbiology↗