Perennial grasses will account for approximately 16 billion gallons of renewable fuels by the year 2022, contributing significantly to carbon and nitrogen sequestration. However, perennial grasses productivity can be limited by severe freezing conditions in some geographical areas, although these risks could decrease with the advance of climate warming, the possibility of unpredictable early cold events cannot be discarded. We conducted a study on the model perennial grass Brachypodium sylvaticum to investigate the molecular mechanisms that contribute to cold and freezing adaption. The study was performed on two different B. sylvaticum accessions, Ain1 and Osl1, typical to warm and cold climates, respectively. Both accessions were grown under controlled conditions with subsequent cold acclimation followed by freezing stress. For each treatment a set of morphological parameters, transcription, metabolite, and lipid profiles were measured. State-of-the-art algorithms were employed to analyze cross-component relationships. Phenotypic analysis revealed higher adaption of Osl1 to freezing stress. Our analysis highlighted the differential regulation of the TCA cycle and the GABA shunt between Ain1 and Osl1. Osl1 adapted to freezing stress by repressing the GABA shunt activity, avoiding the detrimental reduction in fatty acid biosynthesis and the concomitant detrimental effects on membrane integrity.The increase in energy demand coupled with the environmental impact of fossil fuels has led to the expansion of programs using perennial species as an alternative source of energy. In this context, perennial grasses, traditionally used as forage and turf, have become the preferred candidates for biomass cropping systems attributed to their ability to grow under low input conditions and high interception of sunlight 1 . Predictions showed that perennial grasses will account for approximately 16 billion gallons of renewable fuels by the year 2022 2,3 . Perennial grasses have shown to support carbon (C) and nitrogen (N) sequestration in the soil 4-6 , contributing to mitigate climate change and environmental degradation 7-9 . Brachypodium sylvaticum is a perennial grass with a simple genome, self-fertility, a short life cycle, and low growth requirements. Its recently released genome, expression gene atlas 10 and well established genetic transformation have made it an efficient model to study the genetic, molecular, and physiological components of perennial grasses 11,12 .Unfavorable winter conditions, including freezing, limit the geographical range of many important crops and reduce their productivity due to growth repression 13,14 . Low temperatures combined with high light intensity provoke the inhibition of the photosystem II and ROS production leading to oxidative stress 15 . In addition, ice formation in the apoplast induces both, cell membrane integrity stress and osmotic stress 16 . The plant's response to low temperatures involves extensive reprograming of gene expression via transcription factors 17 , resulting in co...