Aluminum-induced alterations of cytosolic calcium concentration and its correlation with other aluminum responses in cultured tobacco cells

Abstract

In order to elucidate a possible role of cytosolic free calcium ion ([Ca²⁺]_cyt) in signal transduction pathway in response to aluminum (Al) accumulated on cell surface, relationship between [Ca²⁺]_cyt status and Al toxicity symptoms was investigated in tobacco cells expressing recombinant aequorin. Compared to control cells, Al-treated cells exhibited two types of transient increase in [Ca²⁺]_cyt :the first one immediately after a start of Al exposure which depended on both Al ion and a decrease in pH by Al exposure, and the second one from 3-h Al exposure which was triggered by mechanical stress (pipetting) and was closely related to a loss of growth capability. These results suggest that the accumulation of Al on cell surface sensitize cells to mechanical stress which causes an increase in [Ca²⁺]_cyt.