The effect of short-term low-temperature treatments on gene expression in Arabidopsis correlates with changes in intracellular Ca2+ levels

The role of changes in intracellular calcium ion concentration ([Ca2+](i)) in low-temperature signal transduction in plants has lately been supported by several studies. An analysis to determine whether the low-temperature-induced increase in cytosolic Ca2+ concentration ([Ca2+](cyt)) could be correlated with a downstream response such as gene expression was carried out. The induction of the low-temperature-regulated gene LTI78 was used as an end point marker of the signal transduction pathway. It was found that this gene is induced by very brief low-temperature exposures and that the induction does not depend on a continuous exposure to low temperature. By altering the cooling rate, different patterns of the Ca2+ response were obtained which could be correlated with different patterns of LTI78 induction. Furthermore, reducing the Ca2+ transients by pre-treatment with the Ca2+ channel blocker La3+ also led to a reduced level of gene induction. The results show that brief exposures to low temperature results in the onset of a signalling pathway that leads to the induction of gene expression. This indicates the involvement of changes in [Ca2+](cyt) in low-temperature signalling leading to LTI78 expression but the presence of multiple signalling pathways is suggested.