Abstract
Boron deficiency causes various symptoms such as growth suppression and unusual development. Recently, we reported the adapted mechanism for boron deficiency by using poplar cells (1/20-B and 0-B) grown in 5 and 0 μM boron concentration medium. In 1/20-B cell, we proposed that pectin methylesterase (PME) activity increased to cleave methyl esters of GalA residues and that newly formed free GalA residues were cross-linked by Calcium bridges. These calcium bridges would compensate for the insufficiency of borate bridging between pectic polysaccharide. In this study, we report the PME activity in normal cell (1/1-B), 1/20-B, 0-B, and 1/20-B cell transferred into MS medium containing 100 μM boron (1/20-BR). The PME activity of 1/20-B and 0-B was 1.6- and 1.5-fold higher than 1/1-B, respectively. The activity of 1/20-BR gradually decreased every subcultures to 1.2-fold of 1/1-B in 5th subculture. These results indicated that the PME activity is affected indirectly by boron supply.
