Biology subjects

Carimi, F.

Publications and source records attributed to Carimi, F..

4 recordsLinked to original sources

bioRxiv2026

Distinct seasonal acclimatisation trajectories characterize transplanted and natural meadow seagrass plants

Successful establishment is a critical determinant of seagrass restoration, yet the molecular mechanisms underlying seedling acclimatisation to natural environments remain poorly understood. Here, we combined seasonal physiological observations, transcriptome profiling, and gene co-expression network analysis to investigate the mechanisms underlying the early post-transplantation phase of Posidonia oceanica, a dominant foundation seagrass species, following transplantation. Transplanted seedlings were compared with plants from adjacent natural meadows over the first six months after transplantation using leaf and root samples collected in spring, summer, and autumn. Tissue identity was the primary driver of transcriptomic variation, but transplanted seedlings remained transcriptionally distinct from plants in natural meadows throughout the study, with roots showing greater divergence than leaves, suggesting tissue-specific trajectories of post-transplantation acclimatisation. The early post-transplantation phase was characterised by the activation of genes associated with RNA processing, transcriptional regulation, and abscisic acid signalling. During a summer marine heatwave (28 {degrees}C), both plant groups induced conserved heat-response pathways, including heat-shock proteins and protein-folding mechanisms. Furthermore, transplanted seedlings maintained higher expression of genes involved in photosystem II repair and photoprotection and exhibited reduced leaf growth and extensive leaf necrosis, consistent with a greater requirement for photosynthetic maintenace under prolonged thermal stress. Gene co-expression network analysis revealed that regulatory networks governing structural integrity, hormone signalling, and defence were more stable in natural meadow plants, while transplanted seedlings progressively reorganized their gene co-expression patterns to resemble those of natural meadow plants, particularly in leaves. Our findings reveal tissue-specific molecular trajectories of acclimatisation during early seedling establishment and identify candidate molecular indicators of field acclimatisation and thermal stress responses, providing new mechanistic insights relevant to seedling-based seagrass restoration under climate change.

plant biology↗

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

Microbial Life Inside Posidonia Seeds: Beneficial En-dophytes and Implications for Marine Plant Health

Plant-microbe interactions are key drivers of plant health and ecosystem functioning, yet their roles in marine environments remain poorly understood. The seagrass Posidonia oceanica, a foundation species in the Mediterranean Sea, forms complex associations with microbial communities that influence its development and stress tolerance. Here, we provide the first evidence of culturable bacterial and fungal endophytes inhabiting P. oceanica seeds collected from central Mediterranean, a region representing a major center of the species genetic diversity. Using two different marine culture media, we isolated a diverse assemblage of endophytes, predominantly affiliated with Marinomonas, Celerinatantimonas, Vibrio, Halomonas, Kocuria, Bacillus, Metabacillus, Lysobacter, and Aureimonas, along with the fungi Paecilomyces maximus and Halophytophthora sp. Most bacterial isolates displayed plant growth-promoting (PGP) traits such as indole-3-acetic acid production and nitrogen fixation, supporting their potential contribution to seed germination and early seedling establishment. The detection of Candidatus Celerinatantimonas neptuna, a nitrogen-fixing symbiont previously described in P. oceanica roots, suggests a possible route of vertical transmission. Although fungal endophytes were less frequent, their presence indicates that P. oceanica seeds may serve as a reservoir of both beneficial and potentially pathogenic taxa. These findings expand our understanding of the P. oceanica holobiont, highlight the role of seeds in the persistence and dissemination of endophytic communities and lay the groundwork for the biotechnological use of seed-associated microbes in marine plant restoration and conservation, and in crop stress tolerance.

microbiology↗

bioRxiv2025

Sustaining Seagrass Restoration: Long-Term Preservation of Posidonia oceanica Seeds and Seedlings

Seagrass restoration efforts using Posidonia oceanica traditionally rely on lateral cuttings, a costly and labor-intensive method that damages parent meadows and limits genetic diversity. Seedling-based propagation presents a viable alternative which ensures genetic variability but is constrained by the unpredictability of seed stranding events and the short window for seed collection. To address this limitation, we tested methods for long-term seed and seedling storage, aiming to extend transplanting opportunities beyond natural germination cycles. We evaluated the effects of light or dark conditions, density, and seedling age on viability during storage at 4{degrees}C for six months. Our results demonstrate that light is essential for preserving viability, as all dark-stored samples died post-storage. Older seedlings (1-2 months old) exhibited higher survival rates (70-90%) compared to freshly collected seeds (40%). Seedling density did not significantly affect viability, simplifying large-scale storage. Attempts to induce dormancy with ABA or paclobutrazol were unsuccessful. This study provides the first successful protocol for seed and seedling storage, enabling year-round planning of seagrass restoration projects and enhancing their feasibility and efficiency.

ecology↗