Relationship between Polyamines and Anaerobic Respiration of Wheat Seedling Root under Water-Logging Stress

To elucidate the relationship between polyamines and anaerobic respiration of wheat (Triticum aestivum L.) seedling root under water-logging stress, the contents of polyamines (PAs), lactate and alcohol, and the activities of anaerobic respiration enzymes were investigated in seedling roots of two wheat cultivars, Yumai no. 18 and Yangmai no. 9. On the 5th day after water-logging treatment, spermidine (Spd) and spermine (Spm) contents increased significantly, pyruvate decarboxylase (PDC) activity increased and there was no difference between two cultivars. Alcohol dehydrogenase (ADH) activity and alcohol content in Yangmai no. 9 increased more markedly than Yumai no. 18, while lactate dehydrogenase (LDH) activity and the lactate content in the Yumai no. 18 increased more markedly than Yangmai no. 9. Treatments with exogenous Spd and Spm resulted in enhancing the increases in ADH activity, alcohol content, and the levels of Spd and Spm. This concomitantly inhibited the increases in LDH activity and lactate content in Yumai no. 18 under water-logging stress, alleviating stress-induced injury to the seedlings. Treatment with exogenous inhibitor methylglyoxyl-bis-guanylhydrazone (MGBG), resulted in reducing the increases in ADH activity, alcohol content, and Spd and Spm levels, promoting the increases in LDH activity and lactate content in Yangmai no. 9 under water-logging stress, and aggravating the stress-induced injury to the seedlings. The results suggested that under water-logging stress, increased Spd and Spm could facilitate the tolerance of wheat seedling to the stress by enhancing the increases in ADH activity and alcohol content, and inhibiting the increases in LDH activity and lactate content.