外源抗坏血酸对臭氧胁迫下水稻叶片膜保护系统的影响

在田间原位条件下,运用OTCs（open top chamber）装置研究了外源抗坏血酸（exogenous ascorbate acid,ExAsA）对臭氧（O3）胁迫下水稻（Oryza Sativa L.）叶片膜保护系统的影响.研究发现,O3胁迫下的水稻叶片经过ExAsA处理后叶绿素a含量显著升高,而叶绿素b含量变化不明显;相对于对照,经ExAsA处理后的水稻叶片过氧化氢（H2O2）和丙二醛（MDA）含量及相对电导率（REC）均降低,超氧化物岐化酶（SOD）和抗坏血酸过氧化物酶（APX）活性明显提高,抗氧化剂类胡萝卜素（Carotene）含量升高.这表明,ExAsA改善了O3胁迫下水稻叶片的抗氧化系统功能,减少了叶片中活性氧（activity oxygen species,AOS）的积累,抑制了脂质过氧化（lipid peroxidation,LP）,延迟了O3对水稻叶片的老化作用,提高了水稻叶片对O3危害的抗性.

Effects of exogenous ascorbate acid on membrane protective system of in situ rice leaves under O3 stress

The ozone is the primary gaseous pollutant with significant adverse effects on vegetation. Those effects include visible leaf injury, growth and yield reductions, accelerated senescence and altering sensitivity to biotic and abiotic stresses. Reductions in photosynthesis rate, stomata conductance, and root/shoot ratio, increase in respiration, and change in crop quality has also been observed in many crops. With fast industrial development, tropospheric ozone in the Yangtze River Delta, in eastern China, has risen since the later of the last century. The elevated ozone has become a prominent environmental and economic issue in this region. In order to alleviate the phytotoxin of elevated level O_3 to crops, the effect of exogenous ascorbate acid (ExAsA) on membrane protective system of rice (Oryza sativa L.) leaves was investigated. Rice was grown in open top chambers (OTCs) under field conditions and exposed to five levels of O_3 treatments: charcoal-filtered air (CF), non-charcoal-filtered air (NF), 50 nl/L, 100 nl/L, and 200nl/L O_3. In addition, half of the plot within the OTC was treated by spraying 0.1% ExAsA solution once per week. The results showed that with spraying ExAsA, chlorophyll a content of rice leaves distinctly increased; H_2O_2 content, membrane permeability (indicated by the relative electrical conductivity, REC), and lipid peroxidation (indicated by the content of Malondialdehyde, MDA) of rice leaves declined; activities of superoxide dismutase (SOD), ascrobate peroxidase (APX), and carotenoid (Car) content increased. From these results, it can speculated that ExAsA defers leaf senescence, reduces accumulation of active oxygen species (AOS) and lipid peroxidation (LP) of leaves, enhances the function of the membrane protective system, and increases the tolerance ability of rice leaves under elevated O_3 exposure.