Effects of aluminum on the growth of tea plant and activation of antioxidant system

A possible connection between the effects of aluminum (Al) on the growth of tea plants and the active oxygen species scavenging system in root tips of intact tea plants and suspension-cultured tea cells was examined. Intact tea plants were treated with or without Al in a modified Hoagland solution, while suspension-cultured tea cells were treated with or without Al in a simple salt solution containing 3% sucrose and 0.2 mM calcium. Compared with the control treatments without Al, the activities of superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) increased by Al both in roots of intact plants and cultured cells. The level of peroxidation of membrane lipids, as well as the activity of wall-bound peroxidas, the content of lignin and wall-bound phenols, however, reduced by the treatment with Al either in tea roots or in cultured tea cells. The results indicated that Al-induced increase in the activities of antioxidant enzymes, resulting in increased membrane integrity and delayed lignification and aging, can be considered as a possible reason for the stimulatory effects of Al on the growth of the tea plants and this is irrespect of the presence of other micronutrients and their interaction with Al.