[Involvement of Ca2+ and calmodulin in the regulation of H2O2-induced heat tolerance in maize seedlings].

Exogenous H(2)O(2) pretreatment significantly increased the endogenous H(2)O(2) content and calmodulin activity in maize seedlings, alleviated rapid loss of calmodulin activity, and raised the survival rate of maize seedlings under heat stress (Figs. 1, 4). The formation of H(2)O(2)-induced heat tolerance in maize seedlings was strengthened by exogenous Ca(2+) treatment, and weakened by Ca(2+) chelator EGTA, plasma-membrame-channel blocker La(3+), intracellular channel blocker ruthenium red, calmodulin antagonists chlorpromazine and trifluoperazine treatment (Figs. 1, 2). These results confirmed that Ca(2+) and calmodulin are involved in the regulation of H(2)O(2)-induced heat tolerance in maize seedlings.