Boron effects on wall polysaccharide composition of marshmallow cells

Marshmallow is a medicinal plant containing mucilage polysaccharides and various phenolic acids. Boron (B) is an essential micronutrient whose necessity for plant growth and development has been attributed to its role in cell wall pectin network and maintenance of integrity and performance of membranes. The present study was aimed to investigate the effects of different concentrations of B (0.01, 0.1, and 1 mM respectively as deficient, sufficient or control, and excess concentrations) on cell wall polysaccharides of suspension-cultured Althaea officinalis cells in a modified LS medium. The results showed that under B deficiency higher ratio of cell production was devoted to produce wall materials (4.4% of fresh weight), compared with normal and excess B supply (2.3% and 1.8% of fresh weights, respectively). Moreover, B deficiency drastically reduced relative contents of hemicellulose A and cellulose (78% and 72%) compared to those of the control cells. No significant change appeared in the relative amount of pectin in cell walls of deficient and excess B treated cells, in comparison with normal concentration of B. Boron deficiency significantly increased hemicellulose B (157% of the control). This may help the cells with increasing sites for B adsorption under insufficient B supply, while improving its health benefit, since hemicellulose contributes to lowering cholesterol and increasing gut bacteria.