Quantitation of ascorbic acid in Arabidopsis thaliana reveals distinct differences between organs and growth phases

Optimal plant growth is the result of the interaction of a complex network of plant hormones and environmental signals. Ascorbic acid (AsA) is a crucial antioxidant in plants and is involved in the regulation of cell division, cell expansion, photosynthesis and hormone biosynthesis. Quantitative analysis of AsA in Arabidopsis thaliana organs was
conducted using HPLC with d -isoascorbic acid (Iso-AsA) as an internal standard. Analysis revealed Àuctuations in the levels of AsA in different organs and growth phases when plants were grown under standard conditions. AsA concentrations increased in leaves in direct proportion to leaf size and age. Young siliques (seed set stage) and Àowering buds (open and unopened) showed the highest levels of AsA. A relationship was found between the level of AsA and indole acetic acid (IAA) in leaves, stems, Àowers, and siliques and the highest level of IAA and AsA
were found in the Àowers. In contrast, the lowest level of the plant hormone, salicylic acid, was found in the Àowers and the highest quantity measured in the leaves. Consequently, AsA has been found to be a multifunctional molecule that is involved as a key regulator of plant growth and development.