Antioxidant Capacity and Damages Caused by Salinity Stress in Apical and Basal Regions of Rice Leaf
Antioxidant Capacity and Damages Caused by Salinity Stress in Apical and Basal Regions of Rice Leaf
复制标题
DOI：
10.1626/pps.12.319
复制
发表时间：
2009-01
影响因子：
2.5
通讯作者：
K. Yamane;Shiro Mitsuya;M. Kawasaki;M. Taniguchi;H. Miyake
中科院分区：
文献类型：
--
作者：
K. Yamane;Shiro Mitsuya;M. Kawasaki;M. Taniguchi;H. Miyake
摘要研究了盐胁迫下水稻叶片顶端和基部对Na+敏感性增强的机制。将三周龄的植物在水培中用200 mM NaCl处理3 d。从完全展开的最上部叶（第6叶片）的顶端和基部区域分别获得6cm长的片段作为老组织和幼组织。在暴露于200 mMNaCl的植物中，硝基蓝四氮唑（NBT）还原活性、H2 O2和丙二醛（MDA）含量显着增加，并伴有顶端区类囊体肿胀和类囊体膜破坏。然而，没有迹象表明在基底区观察到氧化损伤，即使在基底区的Na+含量是在顶端区域。在顶端区域，由于抗坏血酸过氧化物酶和愈创木酚过氧化物酶的组成水平下降，抑制H2O2的能力低于基部区域。除超氧化物歧化酶和愈创木酚过氧化物酶外，其它抗氧化酶活性在NaCl胁迫48 h后均显著下降。相比之下，过氧化氢酶和谷胱甘肽还原酶的活性在基区增加与对照相比，和其他抗氧化酶并没有降低盐度在实验期间。这些结果表明，随着年龄的增长，抑制活性氧的能力下降，因此，叶片的顶端区域遭受Na+的伤害比基部区域。
Abstract We investigated the mechanisms of increased sensitivity to Na+ in the apical and basal regions of the rice leaf under salinity. Three-week-old plants were treated with 200 mM NaCl in hydroponic culture for 3 d. Segments 6 cm in length were obtained from the apical and basal regions of the fully expanded uppermost leaves (6th leaf blades) as old and young tissues, respectively. In the plants exposed to 200 mM NaCl, Nitro blue tetrazolium (NBT) reducing activity, and H2O2 and Malondialdehyde (MDA) contents significantly increased, accompanied by the swelling of thylakoids and destruction of thylakoid membranes in the apical regions. However, no indication of oxidative damages was observed in the basal region, even though the Na+ content in the basal region was comparable to that in the apical region. In the apical region, the capacity to scavenge H2O2 was lower than that in the basal region due to decrease in the constitutive levels of ascorbate peroxidase and guaiacol peroxidase. In addition, the activities of antioxidant enzymes except superoxide dismutase and guaiacol peroxidase decreased drastically after 48 hr of exposure to NaCl. By contrast, the activities of catalase and glutathione reductase in the basal region increased compared with those in the control, and other antioxidant enzymes did not decrease under salinity during the experimental period. These results suggest that the capacity to scavenge reactive oxygen species decreased with age, and thus the apical region of the leaf blade suffered severer damage by Na+ than the basal region.