Changes in peroxidase activity and lignin content of cultured tea cells in response to excess manganese

摘要

The present study was undertaken to identify the effects of manganese (Mn) on the activity of peroxidase(PO) and the amount of ascorbic acid (AsA) and lignin, as well as the cell viability of suspension-cultured teacells (Camellia sinensis L. cv. Yabukita). Cells were grown in B5 medium (containing 0.06 mmol L~(-1) Mn) andcultured for 24 h in medium with a Mn concentration of 0.9 mmol L~(-1) as an excess treatment. No significantdifference was observed between cellular growth and the viability of the cultured tea cells after treatmentwith excess Mn compared with cells grown under control conditions, although the content of Mn in cells inthe excess Mn treatment was 12-fold higher than that of the control cells. The amount of total AsA was alsonot affected by the Mn treatment. The activity of ionically wall-bound peroxidase (IPO) increased in thepresence of excess Mn, unlike the content of lignin. Conversely, the activities of soluble PO and covalentlywall-bound PO decreased with excess Mn. These findings suggested that IPO might contribute to Mntolerance in tea cells. However, its role in the mechanism(s) of Mn tolerance has not been elucidated.