钙对盐胁迫下水稻幼苗抗氧化酶活性和膜脂过氧化作用的影响

研究了外源Ca2 对盐胁迫下耐盐性不同的两个水稻品种(武育粳3号和IR36)几种抗氧化酶活性及膜脂过氧化的影响。结果表明:适量的Ca2 供应能有效提高水稻叶片超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)以及抗坏血酸过氧化物酶(APX)的活性,使之维持在较高的水平上,并降低了丙二醛(MDA)含量和细胞膜透性。此外,外源Ca2 还增加了抗坏血酸(AsA)的含量,增强了水稻幼苗的根系活力。这表明适量的外源Ca2 供应提高水稻耐盐性的原因之一,在于其增强了植株的活性氧清除能力以及对细胞膜的稳定作用。

EFFECT OF EXOGENOUS CALCIUM ON ANTIOXIDANT ENZYME ACTIVITY AND LIPID PEROXIDATION OF RICE SEEDLINGS UNDER SALT STRESS

Two contrasting rice (Oryza sativa L. ) cultivars, i.e. Wuyujing No. 3 (salt-tolerant) and IR36 (salt-sensitive), were used for investigating effects of exogenous calcium (Ca) on antioxidant enzyme activity and lipid peroxidation in leaves of rice growing hydroponically under salt stress. The results show that content of malondialdehyde (MDA) as well as membrane permeability were enhanced under salt stress. Salt stress decreased activities of antioxidant enzymes and contents of antioxidants. Addition of Ca significantly enhanced activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) and ascorbate peroxidase (APX) in the leaves of salt-stressed rice but reduced concentration of MDA and permeability of cell membrane. Furthermore, exogenous Ca enhanced ascorbic acid (AsA) content and root activity. Treatment with higher Ca (10 mmol L -1 Ca 2 ) was observed to have better alleviating effect than that with lower Ca (5 mmol L -1 Ca 2 ) in the two contrasting rice cultivars differing in salt tolerance, but the reverse was observed in the experiment of APX activity. The degree of increase or decrease in the above mentioned parameters was smaller in salt-tolerant cultivar than in salt-sensitive one under single NaCl stress. The results seem to suggest that the elimination of active oxygen species (AOS) and maintenance of membrane stability accounted to some extent for the mechanisms of Ca-mediated enhancement of salt tolerance in rice growing under salt stress.