A recent study reveals how grapevine cells adapt to sugar starvation by reprogramming their DNA methylation and gene expression. Under carbon-deficient conditions, these cells undergo significant metabolic shifts, slowing growth while activating survival mechanisms like autophagy and photosynthesis. The research highlights the critical role of epigenetic changes, particularly increased DNA methylation at transposable elements, in helping cells cope with energy stress. These findings deepen our understanding of plant resilience and could inform strategies to improve crop tolerance to environmental stresses, such as drought or nutrient scarcity.
Plants face constant challenges from fluctuating nutrient availability, which disrupts their growth and survival. Sugar starvation, for instance, triggers metabolic and transcriptional changes, but the role of epigenetic regulation in this process remains poorly understood. Epigenetic mechanisms, such as DNA methylation, are known to influence gene activity without altering the DNA sequence, yet their connection to metabolic stress is unclear. Previous studies in animals and yeast have linked starvation to epigenetic modifications, but evidence in plants is limited. Understanding how plants epigenetically adapt to carbon scarcity could unlock new ways to enhance their stress resilience. Based on these challenges, researchers investigated the interplay between sugar depletion, DNA methylation, and gene expression in grapevine cells.
Published (DOI: 10.1093/hr/uhae277) on January 1, 2025, in Horticulture Research , a study by scientists from the University of Bordeaux and INRAE, including Margot M.J. Berger, Virginie Garcia, Nathalie Lacrampe, and others,explores how grapevine cells respond to sugar starvation. Using Cabernet Sauvignon cell cultures, the team analyzed metabolic, transcriptional, and epigenetic changes under glucose-rich and glucose-poor conditions. The research reveals that carbon deficiency triggers widespread DNA methylation changes, particularly at transposable elements, alongside shifts in gene expression linked to stress survival. These findings underscore the importance of epigenetic regulation in plant adaptation to nutrient scarcity.
The study found that grapevine cells deprived of glucose halted growth within 48 hours and underwent dramatic metabolic reprogramming. Key pathways for biomass production, like cell wall synthesis, were downregulated, while autophagy and photosynthesis genes were activated. Notably, sugar-starved cells showed higher global DNA methylation levels, especially in transposable elements, suggesting a mechanism to stabilize the genome under stress.
Using multi-omics approaches, the team identified 5,607 differentially expressed genes and 848 differentially methylated regions (DMRs). Hyper-methylation in CHH contexts was prominent, linked to reduced cell division and altered small RNA pathways. Intriguingly, some genes involved in carbon metabolism and stress responses exhibited methylation changes in their promoters, correlating with expression shifts. For example, a malate dehydrogenase gene was repressed alongside hyper-methylation of its promoter.
The study also revealed disruptions in one-carbon metabolism, which supplies methyl groups for DNA methylation. Flux analyses showed slowed production of S-adenosylmethionine (SAM), a key methyl donor, hinting at resource reallocation during starvation. These insights highlight how epigenetic and metabolic networks jointly orchestrate plant stress responses.
Dr. Philippe Gallusci, the study's corresponding author, emphasized: "Our work bridges the gap between metabolism and epigenetics in plants. By showing how DNA methylation dynamically responds to carbon scarcity, we uncover a layer of regulation critical for stress adaptation. This could pave the way for breeding crops with enhanced resilience by targeting epigenetic pathways."
The research opens avenues for improving crop tolerance to abiotic stresses, such as drought or poor soil, by manipulating epigenetic markers. Farmers could potentially use metabolic priming or epigenetic editing to enhance plant survival in low-nutrient conditions. Additionally, the findings may inform viticulture practices, helping grapevines withstand climate-induced sugar shortages during ripening. Future studies could explore whether similar mechanisms operate in other crops or under field conditions. By elucidating the epigenetic basis of stress responses, this work contributes to sustainable agriculture strategies aimed at securing food production in a changing climate.
