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

Abstract

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 tea cells (Camellia sinensis L. cv. Yabukita). Cells were grown in B5 medium (containing 0.06 mmol L −1 Mn) and cultured for 24 h in medium with a Mn concentration of 0.9 mmol L −1 as an excess treatment. No significant difference was observed between cellular growth and the viability of the cultured tea cells after treatment with excess Mn compared with cells grown under control conditions, although the content of Mn in cells in the excess Mn treatment was 12-fold higher than that of the control cells. The amount of total AsA was also not affected by the Mn treatment. The activity of ionically wall-bound peroxidase (IPO) increased in the presence of excess Mn, unlike the content of lignin. Conversely, the activities of soluble PO and covalently wall-bound PO decreased with excess Mn. These findings suggested that IPO might contribute to Mn tolerance in tea cells. However, its role in the mechanism(s) of Mn tolerance has not been elucidated.

Changes in the ultrastructure of soybean cultivars in response to manganese supply in solution culture

“…Furthermore, separation of the cell membrane from the cell wall and rupture with formation of many cytoplasmatic vesicles in adjacent spaces can occur. Higher absorption of Mn, as of other heavy metals, probably increases the formation of free radicals, causing thus peroxidative damage of the cell membranes (Morita et al, 2006). The fact that lipid globules were observed in the IAC-15 chloroplasts -small electron-dense lipid globules usually situated along the stroma -at all Mn concentrations could indicate either alteration in the metabolic route of starch synthesis, or this could be a characteristic of the genotype.…”

Genotypic Influence on the Absorption, Use and Toxicity of Manganese by Soybean

“…Furthermore, separation of the cell membrane from the cell wall and rupture with formation of many cytoplasmatic vesicles in adjacent spaces can occur. Higher absorption of Mn, as of other heavy metals, probably increases the formation of free radicals, causing thus peroxidative damage of the cell membranes (Morita et al, 2006). The fact that lipid globules were observed in the IAC-15 chloroplasts -small electron-dense lipid globules usually situated along the stroma -at all Mn rates could indicate either alteration in the metabolic route of starch synthesis, or this could be a characteristic of the genotype.…”

“…This phenomenon is more evident in the roots, which pose a physical barrier to the entrance of the pathogen. Mn is a co-factor for the lyase of phenylalanine and ammonia, producing cinnamic acid and other phenols, besides being a co-factor of peroxidases (Huber & Graham, 1999;Malavolta, 2006;Morita et al, 2006;Thompson & Huber, 2007). The observations by electron transmission microscopy of the root cells of the three cultivars maintained in the solution with Mn concentration of 2.0 μmol L -1 (Fig.…”

“…Plant species and genotypes within the same species can differ widely in the tolerance to high Mn (Foy et al, 1988) as well as in susceptibility to the deficiency when grown under conditions of low Mn availability (Graham, 1988). The mechanisms of tolerance to excess Mn have been associated with oxidation of the Mn in the roots, restricted absorption by the roots and translocation of the excess Mn to the leaves, as well as uniform distribution in the tissues, greater internal tolerance and interaction with other elements (mainly K, Ca, Mg, Fe and Si) and defense mechanisms against oxygen reactive species, such as activation of enzymes like ascorbate peroxidase, catalase, Mnsuperoxide dismutase and glutathione peroxidase (Demirevska-Kepova et al, 2004;Morita et al, 2006). On the other hand, better internal utilization or lower requirement, greater redistribution of Mn, increased rate of absorption, exudation of organic acids, acidification of the rhyzosphere and geometry of the root system have been reported as the main mechanisms responsible for lower susceptibility of Mn deficiency (Graham, 1988;Rengel, 1999).…”

Changes in anatomy and root cell ultrastructure of soybean genotypes under manganese stress

“…The tolerance mechanisms to excess Mn have been ascribed to Mn oxidation in the roots, restricted root uptake and translocation of excess Mn to leaves, as well as uniform distribution in the tissues, greater internal tolerance and interaction with other elements (mainly K, Ca, Mg, Fe, and Si) and defense mechanisms against oxygen reactive species, e.g., the activation of enzymes such as ascorbate peroxidase, catalase, Mn-superoxide dismutase and glutathione peroxidase (Demirevska-Kepova et al, 2004;Morita et al, 2006). On the other hand, better internal utilization or lower requirement, greater Mn redistribution, increased absorption rate, exsudation of organic acids, acidification of the rhyzosphere and geometry of the root system have been cited as mainly responsible for lower susceptibility to Mn deficiency (Graham, 1988;Rengel, 1999).…”