Golestan University, Gorgan
Tarbiat Modares University, Tehran
Boron (B) is a non-metal micronutrient which is essential for plants growth and development. Formation of boron complex with cell wall matrix and phenolic compounds is a definite influence of boron in physiological process. It has been suggested that B-toxicity and deficiency may induce excess production of reactive oxygen species thereby promote defense responses by antioxidant enzymes or non-enzymatic compounds e. g. phenolics. Marshmallow (Althaea officinalis L. ) is a plant whose range of boron requirement has not been reported yet. On the other hand this plant contains valuable flavonoid glycosides, phenolic acids, tannins and flavonoids and has exhibited strong total antioxidant activity as well. The present study was therefore undertaken in order to investigate on the effects of different concentrations of boron on phenolic compounds of suspension-cultured marshmallow cells. The cells were grown in a modified MS medium without glycine and boron was supplied in the form of H3BO3 with the concentrations of 0.1, 0.01, and 1mM as control, deficiency and excess concentrations, respectively. Deficiency and excess boron supply increased the amount of pectin-bound cinnamic acid, ferulic acid, benzoic acid and tannic acid. Boron in 1mM concentration increased H2O2 content of the cells, but had no effect on H2O2 content in deficient concentration, compared to the control group. The flavonoid content of the cells treated with 1 and 0.01 mM B was also higher than of the cell under control condition, but both B- deficiency and excess B led to a similar decrease in anthocyanin content.