Biology subjects

Garcia-Gomez, M. E.

Publications and source records attributed to Garcia-Gomez, M. E..

5 recordsLinked to original sources

bioRxiv2026

Unveiling the Epigenomic Control of Temperature Acclimation in Marine Phytoplankton through Multiomics Integration

Temperature plays a central role in marine phytoplankton biogeographical dynamics, physiology and gene expression. Nonetheless, the transcriptional regulatory mechanisms controlling temperature acclimation in marine phytoplankton are yet to be characterized. Ostreococcus tauri was chosen as a model species for green marine phytoplankton due to its cellular and genomic simplicity, as well as its evolutionary position within the green lineage. In this study, epigenomic and transcriptomic data were integrated to characterize changes induced by temperature in the trimethylation of histone 3 at lysines 27 and 4 (H3K27me3 and H3K4me3) epigenetic marks established by the Polycomb (PcG) and Trithorax group (TrxG) complexes, respectively. H3K27me3 was found to be a repressive mark responding to temperature, showing predominantly significant increased levels at high temperatures. While H3K4me3 was associated with active transcription, presenting less evident variations in cultures acclimated to different temperatures. H3K27me3 was found only marginally associated with transposable elements, being mostly involved in the repression of specific biological processes, such as gene expression control by transcription factors, meiosis, motors proteins and cytoskeletal structures. No significant conservation was found between the H3K27me3 gene targets in the model plant Arabidopsis thaliana and Ostreococcus tauri. Nonetheless, transcriptions factors belonging to the MADS-box, WRKY and AP2 families were consistently repressed by H3K27me3 in both species, unveiling that, although the specific downstream targets of this epigenetic mark have diversified during evolution, its role in modulating higher order regulatory nodes remains evolutionary conserved.

plant biology↗

bioRxiv2026

Inositol Pyrophosphates Mediate Chloroplast Lipid Remodeling and Nuclear Gene Repression during High-Light Acclimation in Chlamydomonas reinhardtii

Microalgae are photosynthetic organisms capable of autotrophic growth. Their applicability in multiple industrial fields has been largely studied, thanks to their ability to fixate CO2 into high added value organic products like fatty acids and carotenoids. However, our understanding of the cellular signaling networks that control carbon flux and acclimation to environmental stress remains incomplete. In this study, we used the Chlamydomonas reinhardtii mutant strain vip1-1, which carries a loss-of-function mutation in the hexakisphosphate kinase re-sponsible for the synthesis of inositol pyrophosphates InsP7 and InsP8 (PP-InsPs), to investi-gate the role of these molecules during high-light acclimation. Our results indicate that PP-InsPs participate in the regulation of carbon storage in the form of starch and their deficiency increases TAGs levels in the algal cells. They also impact chloroplast-specific lipid remodeling by modifying membrane composition and fluidity through fatty acid desaturations and glycer-olipid composition. In addition, our findings suggest that PP-InsPs are involved in chloroplast-nucleus communication, where they coordinate transcriptional repression of photosynthesis associated nuclear genes (PhANGs), fatty acid desaturases and lipid synthases, contributing to cellular acclimation to high light. We also found that PP-InsPs modulating effect extended to protein synthesis and accumulation of Calvin-Benson-Bassham cycle intermediates. Therefore, we propose that PP-InsPs function as integratory molecules that balance carbon allocation between storage and structural pools, in response to environmental cues such as high light. These data uncover a novel function of PP-InsPs in high light acclimation and po-tentially in chloroplast-nucleus communication, providing new insights that may help engineering more resilient and efficient strains.

plant biology↗

bioRxiv2026

Transcriptomic Insights into Drought Tolerance Enhancement in Bread Wheat Induced by a Microalgae-based Biostimulant

Bread wheat (Triticum aestivum) is a staple food crucial for global caloric intake and food security. The current climate emergency demands the development of sustainable agricultural practices, particularly in the context of drought-induced yield reductions in bread wheat. Microalgae-based biostimulants have emerged as promising tools to enhance crop tolerance to drought stress while concurrently mitigating atmospheric CO2 accumulation. This study characterizes the transcriptomic responses to the foliar application of the microalgae-based biostimulant LRMTM in drought-stressed and fully irrigated wheat plants unveiling its mode of action. Drought stress at the tillering stage significantly altered gene expression activating key pathways related to phosphate starvation response (PSR), inositol phosphate signaling, and tocopherol biosynthesis. The application of the microalgae-based biostimulant LRMTM in drought-stressed plants further enhanced the expression of drought-responsive genes, particularly those involved in PSR and carbon fixation. Specific responses to LRMTM treatment in drought-stressed plants were also found related to abscisic acid (ABA) signaling activating genes involved in stomata closure, which plays a critical role in drought tolerance. In fully irrigated plants, LRMTM treatment was also beneficial modulating circadian rhythms, shade avoidance and attenuating stress responses. Phenotypic analysis showed that LRMTM-treated plants exhibited enhanced drought tolerance, increased height and spike length even under fully irrigated conditions. These results indicate that the microalgae-based biostimulant LRMTM not only enhances wheat response to drought but also promotes growth and productivity in both stressed and non-stressed conditions which could contribute to the development of sustainable agriculture in the face of the current climate challenges.

plant biology↗

bioRxiv2024

Inositol polyphosphates regulate resilient mechanisms in the green alga Chlamydomonas reinhardtii to adapt to extreme nutrient conditions

In the actual context of climate changing environments, photosynthetic organisms need to adapt to more extreme conditions. Microalgae can be excellent organisms to understand molecular mechanisms that activate survival strategies under stress. Chlamydomonas reinhardtii signaling mutants are extremely useful to decipher which strategies they use to cope with changeable environments. In this study, we conducted prolonged starvation in wild type and vip1-1 Chlamydomonas cells. The mutant vip1-1 has an altered profile of pyroinositol polyphosphates (PP-InsPs) which are signaling molecules present in all eukaryotes. These molecules have been connected to P signaling in other organisms including plants but their implications in other nutrient signaling is still under evaluation. After prolonged starvation, WT and vip1-1 showed important differences in the levels of chlorophyll and photosystem II (PSII) activity. We also performed a metabolomic analysis under these conditions and found an overall decrease in different organic compounds such as amino acids including arginine and its precursors and tryptophan which is considered as a signaling molecule itself in plants. In addition, we observed significant differences in RNA levels of genes related to nitrogen assimilation that are under the control of NIT2 transcription factor. Overall our data indicate an important role of PP-InsPs in the regulation of nutrient starvation especially regarding N assimilation and C distribution. These data are of great importance for the generation of resilient strains to be used in open ponds and high capacity bioreactors.

plant biology↗

bioRxiv2023

Multiomics responses to seasonal variations in diel cycles in the marine phytoplanktonic picoeukaryote Ostreococcus tauri

Earth tilted rotation and translation around the Sun produce one of the most pervasive periodic environmental signals on our planet giving rise to seasonal variations in diel cycles. Although marine phytoplankton plays a key role on ecosystems and present promising biotechnological applications, multiomics integrative analysis of their response to these rhythms remains largely unexplored. We have chosen the marine picoeukaryote Ostreococcus tauri as model organism grown under summer long days, winter short days, constant light and constant dark conditions to characterize these responses in marine phytoplankton. Although 80% of the transcriptome present diel rhythmicity under both seasonal conditions less than 5% maintained oscillations under all constant conditions. A drastic reduction in protein abundance rhythmicity was observed with 55% of the proteome oscillating. Seasonally specific rhythms were found in key physiological processes such as cell cycle progression, photosynthetic efficiency, carotenoid content, starch accumulation and nitrogen assimilation. A global orchestration between transcriptome, proteome and physiological dynamics was observed with specific seasonal temporal offsets between transcript, protein and physiological peaks.

plant biology↗