Kasajima Ichiro
Institute of Molecular and Cellular Biosciences, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo, Japan.
Department of Agriculture, Iwate University, Ueda 3-18-8, Morioka, Iwate, Japan.
BMC Res Notes. 2017 Apr 26;10(1):168. doi: 10.1186/s13104-017-2489-9.
Oxidative stress is considered to be involved in growth retardation of plants when they are exposed to a variety of biotic and abiotic stresses. Despite its potential importance in improving crop production, comparative studies on oxidative stress tolerance between rice (Oryza sativa L.) cultivars are limited. This work describes the difference in term of oxidative stress tolerance between 72 rice cultivars.
72 rice cultivars grown under naturally lit greenhouse were used in this study. Excised leaf discs were subjected to a low concentration of methyl viologen (paraquat), a chemical reagent known to generate reactive oxygen species in chloroplast. Chlorophyll fluorescence analysis using a two-dimensional fluorescence meter, ion leakage analysis as well as the measurement of chlorophyll contents were used to evaluate the oxidative stress tolerance of leaf discs. Furthermore, fluorescence intensities were finely analyzed based on new fluorescence theories that we have optimized.
Treatment of leaf discs with methyl viologen caused differential decrease of maximum quantum yield of photosystem II (Fv/Fm) between cultivars. Decrease of Fv/Fm was also closely correlated with increase of ion leakage and decrease of chlorophyll a/b ratio. Fv/Fm was factorized into photochemical and non-photochemical parameters to classify rice cultivars into sensitive and tolerant ones. Among the 72 compared rice cultivars, the traditional cultivar Co13 was identified as the most tolerant to oxidative stress. Koshihikari, a dominant modern Japonica cultivar in Japan as well as IR58, one of the modern Indica breeding lines exhibited a strong tolerance to oxidative stress.
Close correlation between Fv/Fm and chlorophyll a/b ratio provides a simple method to estimate oxidative stress tolerance, without measurement of chlorophyll fluorescence with special equipment. The fact that modern cultivars, especially major cultivars possessed tolerance to oxidative stress suggests that oxidative stress tolerance is one of the agricultural traits prerequisite for improvement of modern rice cultivars. Data presented in this study would enable breeding of rice cultivars having strong tolerance to oxidative stress.
当植物暴露于各种生物和非生物胁迫时，氧化应激被认为与植物生长迟缓有关。尽管氧化应激在提高作物产量方面具有潜在重要性，但关于水稻（Oryza sativa L.）品种间氧化应激耐受性的比较研究却很有限。这项工作描述了72个水稻品种在氧化应激耐受性方面的差异。
本研究使用了在自然光照温室中种植的72个水稻品种。将离体叶圆片置于低浓度的甲基紫精（百草枯）中，甲基紫精是一种已知能在叶绿体中产生活性氧的化学试剂。使用二维荧光计进行叶绿素荧光分析、离子渗漏分析以及叶绿素含量测定，以评估叶圆片的氧化应激耐受性。此外，基于我们优化的新荧光理论对荧光强度进行了精细分析。
用甲基紫精处理叶圆片导致各品种间光系统II最大量子产率（Fv/Fm）出现不同程度的下降。Fv/Fm的下降也与离子渗漏的增加和叶绿素a/b比值的降低密切相关。通过将Fv/Fm分解为光化学和非光化学参数，将水稻品种分为敏感型和耐受型。在72个被比较的水稻品种中，传统品种Co13被确定为对氧化应激耐受性最强。日本的主要现代粳稻品种越光以及现代籼稻育种系之一的IR58对氧化应激表现出较强的耐受性。
Fv/Fm与叶绿素a/b比值之间的密切相关性提供了一种简单的方法来估计氧化应激耐受性，无需使用特殊设备测量叶绿素荧光。现代品种，尤其是主要品种具有氧化应激耐受性这一事实表明，氧化应激耐受性是现代水稻品种改良的农业性状前提之一。本研究提供的数据将有助于培育对氧化应激具有强耐受性的水稻品种。
