| In the present study, the aseptic seedlings of Potamogeton crispus L. were selected as the experimental material and the Cu were used as the stress factor. These aseptic seedlings of P. crispus were cultivated in solution containing different concentrations of Cu under lab condition. The changes of physiological characteristics in the aseptic seedlings of P. crispus were investigated by applying technology of plant physiology and biochemistry.The results are as follow:(1) The young stems with buds of P. crispus have been proved to be easy to induce bud differentiation. Explants were disinfected by5%hydrogen peroxide15min and then10%sodium hypochlorite30second and cut to parts about8mm, which the survival rate was the highest, and the microbiological contamination was the lowest. MS medium including6-BA (2.0mg-L-1) and IBA (0.5mg-L-1) was the most suitable for the bud differentiation. MS medium including6-BA (2.0mg-L-1) was the secondary culture medium.1/10Hoagland sterile nutrient medium was suitable for the growth of the root. Aseptic seedlings of P. crispus were cultured in the conditions of25℃,16h day light and1200-1500lx light intensity.(2) The effects of different concentrations of Cu(0、1、2、4、8、12μmol·L-1) on the metabolism of reactive oxygen, soluble protein content, photosynthetic pigment content and mineral nutrient content of aseptic seedlings of P. crispus were investigated. With the increasing of Cu concentration, the results indicated that:①The generation rate of O2and the content of H2O2and MDA increased.②Superoxide dismutase (SOD) activity increased markedly, while the activities of peroxidase (POD) and catalase (CAT) increased progressively followed by a decline.③The contents of ascobate (AsA) and reduced glutathione (GSH) increased initially and then decreased.④Soluble protein content decreased promptly after a transient inceease.⑤Chlorophyll(Chl) a, chlorophyll b, total chlorophyll and carotenoid contents showed the same trend, which decreased rapidly.⑥the mineral nutrient absorption was affected by Cu stress, the contents of Ca, P, K, Mg and Mn all increased first and then decreased. Cu stress reduced the absorption of Na and Zn, Meanwhlie, the content of Fe increased in varying degrees. Our results suggested that Cu stress induced obvious oxidative damage and disorder of physiological and biochemical metabolism in aseptic seedlings of P. crispus. The up-regulation of antioxidant enzymes activities was good for aseptic seedlings of P. crispus resist Cu stress, but the higher concentrations of Cu stress almost destory aseptic seedlings of P. crispus.(3) The effects of different concentrations of Cu(0、1、2、4、8、12μmol·L-1) on the metabolism of polyamine (PAs) of aseptic seedlings of P. crispus were investigated. With the increasing of Cu concentration, the results indicated that:①Free putrescine (Put) content first enhanced and then reduced notably. However, the contents of free spermidine (Spd) decreased gradually and spermine (Spm) increased significantly. Therefore, the ratio of free (Spd+Spm)/Put promptly increased under high concentrations of Cu treatment. The changes of total PAs contents were similar to those on free PAs.②Perchloric acid soluble conjugated (PS-conjugated) Put and Spm changed in the same pattern as free PAs. While PS-conjugated Spd content increased slightly.③The contents of perchloric acid insoluble bound (PIS-bound) Put and Spd first increased and then decreased, but they were still higher than the control. While, PIS-bound Spm content declined.④With the increase of Cu concentration, the activity of arginine decarboxylase (ADC) sharply decreased after a transient increase, while the activity of ornithine decarboxylase (ODC) did not change significantly. Polyamine oxidase (PAO) and diamine oxidase (DAO) activities increased gradually and then decreased. Our results suggested that Cu stress disturbed metabolic balance of polyamines.The up-regulation of Spm content, the changes of Put into Spd and Spm as well as the conversion between different forms of polyamines played a key role in the adaptation mechanism of aseptic seedlings of P. crispus under Cu stress.(4) Changes of Ca2+-ATPase activity, Na+K+-ATPase activity, Cu and mineral nutrient contents of aseptic seedlings of P. crispus subcellular components under different concentration of Cu(0、1、2、4、8、12μmol·L-1) were investigated. With the increasing of Cu concentration, the results showed that:①chloroplast and soluble fraction Ca2+-ATPase activities decline gradually, while the activity of mitochondrion Ca2+-ATPase increased a little.②Chloroplast Na+K+-ATPase activity decreased promptly after a transient increase, mitochondrion Na+K+-ATPase activity increased gradually, while the activity of soluble fraction Na+K+-ATPase decreased rapidly.③With the rise of Cu concentration, contents of Cu increased significantly in all subcellular components of aseptic seedlings of P. crispus, and Cu mainly distributed in soluble fraction, less in chloroplast and mitochondria.④In soluble fraction, the content of Ca2+rised, Na+content first increased and then decreased, while K+content declined gradually. The conclusion could be reached that:In aseptic seedlings of P. crispus, Cu stress led to the accumulation of Cu in subcellular components, disturbed the function of Ca2+-ATPase and Na+K+-ATPase, disordered the absorption, transport and metabolism of mineral nutrient and resulted in the accumulation of Ca2+, which all caused damage to cells. |
PDF Full Text Request