Heat shock induces cross adaptation to aluminum stress through enhancing ascorbate-glutathione cycle in wheat seedlings.

Aluminum (Al), a neurotoxin agent, is universal in the earth crust, but its bioavailability and toxicity are manifested under acidic conditions. Up to 60% of the acid soils are distributed in tropical and subtropical regions, where crops simultaneously experience heat-shock stress. Here, we investigated the effects of heat shock-priming on Al tolerance in two different wheat genotypes. Conditioning of wheat seedlings with short period high temperature significantly alleviated Al-induced root growth inhibition, but did not significantly affect Al accumulation. However, we observed that heat shock-primed roots maintained lower levels of lipid peroxidation and higher cell viability. These priming-triggered effects were associated with reactive oxygen species (ROS) homeostasis. Furthermore, conditioning of plants with high temperature increased the contents of reduced ascorbate and glutathione, and ratios of reduced to oxidized forms of these molecules in wheat roots. However, ascorbate or glutathione biosynthesis inhibitors markedly prevented heat shock priming-induced ROS reduction accompanied by aggravated root elongation. Moreover, heat shock-priming enhanced the metabolic intensity of ascorbate-glutathione cycle, as activities of the cycle-allied enzymes were significantly increased. These results suggest that heat-shock induces cross adaptation to Al toxicity through sustaining efficient ascorbate-glutathione cycle operation in wheat plants.