| heal.abstract |
Plants exposed to limited water availability respond with a series of developmental, morphological, biochemical and molecular adaptations, aiming at safeguarding basal levels of metabolic activity. Given that sorghum (Sorghum bicolor L. Moench) is regarded as a drought-tolerant species, it provides an ideal model to study the molecular and physiological mechanisms underlying such tolerance. Young sorghum seedlings grown under controlled conditions were subjected to drought stress, induced by polyethylene glycol (PEG) 6000 at two levels of stress (2.5% and 5% PEG), for 7 days. Non-stressed plants were also included as controls. Metabolite profiling on leaves and roots of stressed and control plants was performed by Gas-chromatography combined with Mass-spectrometry (GC-MS). For each treatment and tissue type, four biological replications were conducted. In total, the analysis yielded 143 quantifiable compounds with highly reproducible patterns. Comparative metabolite profiling of stressed versus control plants revealed that drought stress substantially alters the metabolite content in both leaves and roots. In leaves, most profound alterations were observed in compounds belonging to the group of sugars, including D-mannose, D-glucose, isomaltose, fructose and sucrose, but also myo-inositol and L-asparagine whereas in roots, most influencing compounds were certain sugars, such as D-glucose, fructose, sucrose and D-(+)trehalose, as well as D-mannitol. Deduced metabolomics data are discussed and suggested as functional tools towards understanding the underlying regulatory networks involved in the physiology of drought tolerance in sorghum. |
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