Effects Of Abiotic Stresses On Arginine Metabolism In Roots Of Malus Hupehensis Rehd

In this paper, we studied the annual periodic variations of free arginine content, nitric oxide generation rate and the effects of salt stress, drought stress, low-temperature stress and cadmium stress on arginine metabolism in trees or seedlings of Malus hupehensis Rehd.. At the same time we studied the effects of polyamines and nitric oxide on alleviating salt or Cadmium stress-induced membranaceous lipid peroxidation.The main results were as follows:1. The content of free arginine increased gradually from stem apex to root apiex in trees of Malus hupehensis Rehd. in winter; the content of free arginine in xylem was higher than that in phloem; the content of free arginine in thick root was higher than that in fine root; the content of free arginine was highest in winter but lowest in august and september yearly. The generation rate of nitric oxide was highest in summer, but lowest in winter. The generation rate of nitric oxide in xylem was higher than that in phloem. The generation rate of nitric oxide was high in quicking growth root.2. Arginase, ADC and ODC activities were elevated by salt stress, drought stress and cadmium stress in seedlings of Malus hupehensis Rehd.. ADC and ODC activities, putrescine content, nitric oxide generation rate and NOS activity were enhanced gradually with the increasing concentration of stresses. But ADC and ODC activities were all restrained under 300 mM NaCl, 20% PEG or 200μM CdCl2.3. The activities of arginase, ODC and ADC were elevated but spermidine content decreased gradually with the accumulation of chilling. NOS activity was retained after continuing increase of chilling in three days.4. 200μM Put, Spd, Spm restrained the increased content of MDA under salt stress or without stess, and thus alleviating the salt stress-induced lipid peroxidation. Among the above three polyamines, the spermine had the best effect on mitigating the lipid peroxidation. 200μM SNP depressed the content of MDA under 200μM cadmium chlorine, and then ameliorating the peroxidation of lipid.