Chilling Tolerance of Wheat Seedlings Is Related to an Enhanced Alternative Respiratory Pathway

Pretreatment with exogenous hydrogen peroxide (H2O2) mitigated the water loss of wheat leaves exposed to 4 degrees C for 24 h. The same treatment also partially reduced the increases of electrolyte leakage and H2O2 production of the chilled plants. These observations suggest that H2O2 pretreatment could effectively induce chilling tolerance. The capacity of the alternative respiratory pathway and the expression of the gene encoding the alternative oxidase (AOX1) were substantially elevated by H2O2 treatment under either normal or chilling conditions. Salicylhydroxamic acid (SHAM, an inhibitor of the alternative respiratory pathway) decreased the tolerance of plants to chilling conditions and reversed the chilling tolerance induced by exogenous application of H2O2. These observations indicate that the tolerance of plants to chilling might be related to an enhanced alternative respiratory pathway.