Micropropagation has become a widely used technique for rapidly propagating and large-scale plants. Over the past 30 years, great progress has been made to develop and optimize micropropagation methods and culture media enabling the large-scale multiplication of a large number of plant species. However, despite the improved propagation efficiency, the process still faces many problems, which in some cases limit the profitability of the technique. Indeed, in vitro seedlings present numerous aberrations such as stomatal dysfunction, poor epicuticular wax deposition, somaclonal variation, poor rooting and hyperhydricity. Many species cannot be propagated profitably by tissue culture due to these induced anatomical and physiological changes (which lead to excessive loss during hardening). These developmental problems arise from the particular conditions in which the plants are grown. Indeed, the in vitro culture environment is generally characterized by low lighting, poor gas exchange, high relative humidity and high mineral and sugar contents. Yet, even though seedlings receive all essential trophic elements and are grown under constant temperature and light, they appear to suffer from many types of stress. Over the years, sugar has been considered an essential component of in vitro plant cultivation. AVERAGE. However, in addition to its nutritional role, sugar regulates many important metabolic processes associated with plant growth and development (signaling functions). At the cellular level, sugars are essential for intermediate and respiratory metabolism and constitute the substrate for the synthesis of complex carbohydrates such as starch and cellulose. Additionally, sugars provide the precursors to amino acids...... middle of paper ......e to understand plant physiology by obtaining a more holistic picture of biochemical composition. In a seminal work, Roessner et al. (2000) used GC-MS to obtain a comprehensive metabolic profile of simple extracts of soil or potato tubers grown in vitro. About 77 metabolites from various biochemical groups were detected and quantified at the same time. This analytical method proved to be powerful and allowed the simultaneous analysis of a large set of metabolites and revealed major differences between tubers of different origins. Using the same technique, Jeong et al. (2004) showed that 64 metabolites accumulated differentially during the sink-to-source transition in aspen leaves, two-thirds of which exhibited more than 4-fold changes in relative abundance. In this case, metabolic profiling of three leaf stages yielded distinct biochemical phenotypes..