Impact of Drought on Soluble Sugars and Free Proline Content in Selected <i>Arabidopsis</i> Mutants
2020
Libero Gurrieri | Martina Merico | Paolo Trost | Giuseppe Forlani | Francesca Sparla
Water shortage is an increasing problem affecting crop yield. Accumulation of compatible osmolytes is a typical plant response to overcome water stress. Sucrose synthase 1 (SUS1), and glucan, water dikinase 2 (GWD2) and δ<sup>1</sup>-pyrroline-5-carboxylate synthetase 1 (P5CS1) are members of small protein families whose role in the response of <i>Arabidopsis thaliana</i> plants to mild osmotic stress has been studied in this work. Comparative analysis between wild-type and single loss-of-function T-DNA plants at increasing times following exposure to drought showed no differences in the content of water-insoluble carbohydrate (i.e., transitory starch and cell wall carbohydrates) and in the total amount of amino acids. On the contrary, water-soluble sugars and proline contents were significantly reduced compared to wild-type plants regardless of the metabolic pathway affected by the mutation. The present results contribute to assigning a physiological role to GWD2, the least studied member of the GWD family; strengthening the involvement of SUS1 in the response to osmotic stress; showing a greater contribution of soluble sugars than proline in osmotic adjustment of <i>Arabidopsis</i> in response to drought. Finally, an interaction between proline and soluble sugars emerged, albeit its nature remains speculative and further investigations will be required for complete comprehension.
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