Studies On Mechanisms Of Sodium Nitroprusside Ameliorating Aluminum Toxicity In Rye And Wheat

Aluminum (Al) is one of leading factor of restricting plant growth in acidic soil. As a signal messenger, nitric oxide (NO) has been suggested a putative role as an anti-stress molecule in plants by reason of its ability to reduce the oxidative injury produced by biotic and abiotic stress, but there are less reports about the effect and regulating mechanism of NO on Al stress. To elucidate the effect and mechanism of exogenous NO on Al stress, the effects of exogenous NO donor (sodium nitroprusside, SNP) on oxidative response, respiration function in mitochondria, physiological activity in root system and Al adsorption of cell walls in root apex of rye(King, aluminum-tolerant) and wheat(Jinmai47, aluminum-sensitive) were studied under Al stress. The results indicate as follow.1. Root growths of rye and wheat were inhibited under Al stress, it was more seriously along with Al treated concentration increasing, and that of wheat was more seriously than that of rye. Superoxide anion radical (O₂·^-)formation rate and MDA content, which had the highest values at 50 μmol·L^-1, increased under Al stress. Root and leaf H₂O₂ contents increased under Al stress, with the highest value occurring at 50 μmol·L^-1 for leaves, and at 25 μmol·L^-1 for roots. Compared with the controls, the activities of SOD, POD and CAT, and soluble protein contents in rye roots and leaves increased. To keep reactive oxygen species concentration at some range and avoid its damage was one of possible mechanisms for Al-tolerance of rye.2. SNP could ameliorate inhibiting effects of Al on rye and wheat root growth. 1 mmol·L^-1 SNP improved root growth of rye and wheat under Al stress, but higher concentration SNP (>1.5 mmol·L^-1) had inhibiting effect. SNP decreased the contents of ·OH, O₂·^- and MDA, the activities of SOD, APX, the oxidative level of root apex under Al stress.3. Respiratory rate, P/O, OPR, R₃, R₄ and RCR of root tips from rye and wheat decreased, as well as the activities of H⁺-ATPase, H⁺-PPase, Na⁺-K⁺-ATPase, Ca²⁺-ATPase and Mg²⁺-ATPase, but they increased with SNP treatment. It showed that mitochondrial...