Institute of Biology, Komi Scientific Centre, Ural Branch, Russian Academy of Sciences, Syktyvkar, Russia.
Int J Radiat Biol. 2022;98(1):60-68. doi: 10.1080/09553002.2022.1998712. Epub 2021 Nov 11.
High doses of gamma (γ) irradiation cause oxidative stress and DNA damage. Alternative oxidase (AOX) catalyzes the energy-dissipating cyanide-resistant alternative pathway in plant mitochondria and is an important part of the cellular defense network under stress conditions. In this study, plants with an altered expression of the gene were exposed by high dose-rate ionizing radiation to assess the expression of genes of DNA repair and pro-/antioxidant states to elucidate the functional significance of AOX in plant stress response.
Five-week-old plants, either with basal gene expression (wild-type Colombia-0 (Col-0)), antisense silencing of (AS-12), and overexpression of the gene (XX-2), were γ-irradiated at a dose of 200 Gy. Gene expression and biochemical analyses were performed 12 h after irradiation.
Acute γ-irradiation caused different responses between the genotypes. XX-2 plants, either control or irradiated, showed the highest expression of gene and AOX protein, and the lowest expression of DNA repair genes. Wild type and AS-12 plants exposed to γ-irradiation upregulated another stress-induced gene, , and DNA repair genes. Furthermore, a higher activity of Mn-dependent superoxide dismutase (Mn-SOD) was observed in the irradiated AS-12 plants than in the untreated plants of this line. However, AS-12 plants were less effective than Col-0 plants in controlling the accumulation of the superoxide anion. XX-2 plants had the lowest reactive oxygen species (ROS) levels among the genotypes.
AS-12 plants display a compensatory mechanism by increasing the expression of and the synthesis of the AOX protein, as well as by Mn-SOD activation. However, these were insufficient to maintain the background level of embryonic lethal mutations, and thereby the reproductive capacity. These results highlight the importance of AOX in the successful adaptation of plants to acute γ-irradiation, and indicate that plays a key role in the regulation of the stress response.
高剂量的γ（γ）辐照会引起氧化应激和 DNA 损伤。交替氧化酶（AOX）催化植物线粒体中能量耗散的氰化物抗性替代途径，是应激条件下细胞防御网络的重要组成部分。在这项研究中，通过高剂量率离子辐射暴露改变 基因表达的 植物，以评估 DNA 修复和前/抗氧化状态基因的表达，以阐明 AOX 在植物应激反应中的功能意义。
对 5 周龄具有基础 基因表达（野生型哥伦比亚-0（Col-0））、 基因反义沉默（AS-12）和基因过表达（XX-2）的 植物进行γ-辐照，剂量为 200Gy。辐照后 12 小时进行基因表达和生化分析。
急性γ辐照导致不同基因型之间的不同反应。XX-2 植物，无论是对照还是辐照，均表现出最高的 基因和 AOX 蛋白表达，以及最低的 DNA 修复基因表达。暴露于γ辐照的野生型和 AS-12 植物上调了另一个应激诱导基因 ，以及 DNA 修复基因。此外，辐照后的 AS-12 植物比未经处理的该系植物中 Mn 依赖性超氧化物歧化酶（Mn-SOD）的活性更高。然而，AS-12 植物在控制超氧阴离子积累方面不如 Col-0 植物有效。XX-2 植物在基因型中具有最低的活性氧（ROS）水平。
AS-12 植物通过增加 和 AOX 蛋白的合成，以及 Mn-SOD 的激活，表现出一种补偿机制。然而，这些不足以维持胚胎致死突变的背景水平，从而影响生殖能力。这些结果突出了 AOX 在植物成功适应急性γ辐照中的重要性，并表明 在调节应激反应中起关键作用。
