Cc. Subbaiah et al., MITOCHONDRIAL CONTRIBUTION TO THE ANOXIC CA2-CULTURED CELLS( SIGNAL IN MAIZE SUSPENSION), Plant physiology (Bethesda), 118(3), 1998, pp. 759-771
Anoxia induces a rapid elevation of the cytosolic Ca2+ concentration (
[Ca2+](cyt)) in maize (Zea mays L.) cells, which is caused by the rele
ase of the ion from intracellular stores. This anoxic Ca2+ release is
important for gene activation and survival in O-2-deprived maize seedl
ings and cells. In this study we examined the contribution of mitochon
drial Ca2+ to the anoxic [Ca2+](cyt) elevation in maize cells. Imaging
of intramitochondrial Ca2+ levels showed that a majority of mitochond
ria released their Ca2+ in response to anoxia and took up Ca2+ upon re
oxygenation. We also investigated whether the mitochondrial Ca2+ relea
se contributed to the increase in [Ca2+](cyt) under anoxia. Analysis o
f the spatial association between anoxic [Ca2+](cyt) changes and the d
istribution oi mitochondrial and other intracellular Ca2+ stores revea
led that the largest [Ca2+](cyt) increases occurred close to mitochond
ria and away from the tonoplast. In addition, carbonylcyanide p-triflu
oromethoxyphenyl hydrazone treatment depolarized mitochondria and caus
ed a mild elevation of [Ca2+](cyt) under aerobic conditions but preven
ted a [Ca2+](cyt) increase in response to a subsequent anoxic poise. T
hese results suggest that mitochondria play an important role in the a
noxic elevation of [Ca2+](cyt) and participate in the signaling of O-2
deprivation.