State Key Laboratory of Biocontrol and Guangdong Key Laboratory of Plant Resource, School of Life Sciences, Sun Yat-Sen University, Guangzhou, 510275, China.
J Exp Bot. 2012 Jun;63(11):4107-21. doi: 10.1093/jxb/ers093. Epub 2012 Apr 2.
Reactive oxygen species (ROS) are toxic by-products generated continuously during seed desiccation, storage, and germination, resulting in seed deterioration and therefore decreased seed longevity. The toxicity of ROS is due to their indiscriminate reactivity with almost any constituent of the cell, such as lipids, proteins, and DNA. The damage to the genome induced by ROS has been recognized as an important cause of seed deterioration. A prominent DNA lesion induced by ROS is 7,8-dihydro-8-oxoguanine (8-oxo-G), which can form base pairs with adenine instead of cytosine during DNA replication and leads to GC→TA transversions. In Arabidopsis, AtOGG1 is a DNA glycosylase/apurinic/apyrimidinic (AP) lyase that is involved in base excision repair for eliminating 8-oxo-G from DNA. In this study, the functions of AtOGG1 were elaborated. The transcript of AtOGG1 was detected in seeds, and it was strongly up-regulated during seed desiccation and imbibition. Analysis of transformed Arabidopsis protoplasts demonstrated that AtOGG1-yellow fluorescent protein fusion protein localized to the nucleus. Overexpression of AtOGG1 in Arabidopsis enhanced seed resistance to controlled deterioration treatment. In addition, the content of 8-hydroxy-2'-deoxyguanosine (8-oxo-dG) in transgenic seeds was reduced compared to wild-type seeds, indicating a DNA damage-repair function of AtOGG1 in vivo. Furthermore, transgenic seeds exhibited increased germination ability under abiotic stresses such as methyl viologen, NaCl, mannitol, and high temperatures. Taken together, our results demonstrated that overexpression of AtOGG1 in Arabidopsis enhances seed longevity and abiotic stress tolerance.
活性氧（ROS）是种子脱水、储存和萌发过程中不断产生的有毒副产物，导致种子劣化，从而降低种子的寿命。ROS 的毒性是由于它们与细胞的几乎任何成分（如脂质、蛋白质和 DNA）的无差别反应性。ROS 诱导的基因组损伤已被认为是种子劣化的一个重要原因。ROS 诱导的一个突出的 DNA 损伤是 7,8-二氢-8-氧鸟嘌呤（8-oxo-G），它可以在 DNA 复制过程中与腺嘌呤而不是胞嘧啶形成碱基对，导致 GC→TA 颠换。在拟南芥中，AtOGG1 是一种 DNA 糖苷酶/脱嘌呤/脱嘧啶（AP）核酸内切酶，参与碱基切除修复，从 DNA 中消除 8-oxo-G。本研究详细阐述了 AtOGG1 的功能。在种子中检测到 AtOGG1 的转录本，并且在种子脱水和吸胀过程中强烈上调。转化的拟南芥原生质体分析表明，AtOGG1-黄色荧光蛋白融合蛋白定位于细胞核。在拟南芥中超表达 AtOGG1 增强了种子对可控劣化处理的抗性。此外，与野生型种子相比，转基因种子中的 8-羟基-2'-脱氧鸟苷（8-oxo-dG）含量降低，表明 AtOGG1 在体内具有 DNA 损伤修复功能。此外，转基因种子在甲基紫精、NaCl、甘露醇和高温等非生物胁迫下表现出更高的萌发能力。总之，我们的结果表明，在拟南芥中超表达 AtOGG1 增强了种子的寿命和非生物胁迫耐受性。
