Cavalcanti Fabio Rossi, Lima João Paulo Matos Santos, Ferreira-Silva Sérgio Luiz, Viégas Ricardo Almeida, Silveira Joaquim Albenisio Gomes
Laboratório de Metabolismo de Plantas, Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, CP 6033, CEP 60451-970, Fortaleza, Ceará, Brazil.
J Plant Physiol. 2007 May;164(5):591-600. doi: 10.1016/j.jplph.2006.03.004. Epub 2006 May 11.
In this study, we compare some antioxidative responses of leaves and roots associated to growth reduction in cowpea plants (Vigna unguiculata) during short-term salt stress and recovery. The salt treatment was imposed (200 mM NaCl) for six consecutive days and the salt withdrawal after 3 d. The salt treatment caused an almost complete cessation in the relative growth rate of both leaves and roots. Although NaCl withdrawal has induced an intense reduction in the Na(+) content from the leaves and roots, the growth recovery was slight, after 3 d. The leaf lipid peroxidation was increased in salt-stressed plants and slightly reduced in recovered plants after 3 d. Surprisingly, in the salt-stressed roots it decreased markedly after 3 d treatment and in the pre-stressed/recovered roots it was restored to levels near to the control. In leaves, catalase (CAT) activity showed a rapid and prominent decrease after 1 d of NaCl treatment and salt withdrawal had no effect on its recovery. In contrast, the root CAT activity was not changed by effects of both NaCl and salt withdrawal, over time interval. Leaf superoxide dismutase (SOD) activity did not change in all treatments, whereas in roots it significantly decreased after 3 d of salt treatment and recovered after NaCl withdrawal. Contrasting to the other enzymes, the guaiacol-peroxidase activity increased in leaves and roots, reaching almost 200% of control values and it significantly decreased in both organs from the pre-stressed/recovered plants. In conclusion, cowpea roots and leaves present distinct mechanisms of response to lipid peroxidation and CAT and SOD activities during salt stress and recovery. However, these responses and/or the oxidative damages caused by reactive oxygen species were not related with the growth reduction.
在本研究中，我们比较了豇豆植株（豇豆）在短期盐胁迫及恢复过程中，叶片和根系与生长减缓相关的一些抗氧化反应。连续六天施加盐处理（200 mM NaCl），3天后去除盐分。盐处理导致叶片和根系的相对生长速率几乎完全停止。尽管去除NaCl后，叶片和根系中的Na(+)含量大幅降低，但3天后生长恢复仍很轻微。盐胁迫植株的叶片脂质过氧化增加，3天后恢复植株的脂质过氧化略有降低。令人惊讶的是，盐胁迫3天后，根系脂质过氧化显著降低，而预胁迫/恢复后的根系脂质过氧化恢复到接近对照的水平。在叶片中，NaCl处理1天后，过氧化氢酶（CAT）活性迅速显著下降，去除盐分对其恢复没有影响。相比之下，在整个时间间隔内，根系CAT活性不受NaCl和去除盐分的影响。叶片超氧化物歧化酶（SOD）活性在所有处理中均未改变，而在根系中，盐处理3天后显著下降，去除NaCl后恢复。与其他酶不同，愈创木酚过氧化物酶活性在叶片和根系中均增加，几乎达到对照值的200%，而在预胁迫/恢复植株的两个器官中均显著下降。总之，豇豆的根系和叶片在盐胁迫及恢复过程中，对脂质过氧化以及CAT和SOD活性呈现出不同的反应机制。然而，这些反应和/或活性氧引起的氧化损伤与生长减缓无关。
