Document Type : Original Research Papers
Department of Plant Biology, Faculty of Biological Science, Tarbiat Modares University, Tehran, Iran
Faculty of Agriculture, Vali-E-Asr University, Kerman, Iran
Effects of excess concentrations of boron on major cell wall components of tobacco cells
(Nicotiana tabacum L. cv. Burley 21) were studied. Pectin, xyloglucan, hydroxyproline-rich
glycoproteins (extensin), and arabinogalactan proteins were characterized. Results showed
that increased boron supply resulted in significant decrease in cell and cell wall dry weights.
Also, high concentrations of boron reduced relative amounts of major wall components.
Compared with the normal conditions, increase in certain sugars in pectin (e.g., xylose and
its methylated derivative) and decrease in glucose, arabinose, and rhamnose in those treated
cells with higher concentrations of boron was significant. The content of hydroxyprolinerich
glycoproteins decreased when tobacco cells were supplied with higher concentrations of
boron. In these cells, increased ratio of protein to glycan part and increase in hydroxyl lysine
among other amino acids were noticeable. Amount of arabinogalactan proteins also decreased
as boron supply increased. Excess boron did not alter the composition and concentration of
amino acids of arabinogalactan; however, it remarkably increased xylose and glucose but
decreased galactose and arabinose concentrations.