Jung In Jung, Hwang Jung Eun, Han Sung Min, Kim Dong Sub, Ahn Joon-Woo, Choi Hong-Il, Kwon Soon-Jae, Kang Si-Yong, Kim Jin-Baek
a Advanced Radiation Technology Institute, Korea Atomic Energy Research Institute , Jeongeup , Jeollabuk , Republic of Korea.
b Division of Ecological Conservation, Bureau of Ecological Research , National Institute of Ecology , Seocheon , Republic of Korea.
Int J Radiat Biol. 2017 Jul;93(7):717-725. doi: 10.1080/09553002.2017.1297901. Epub 2017 Mar 16.
Exposure to ionizing radiation induces plant defenses by regulating the expression of response genes. The systemic acquired resistance deficient 1 (SARD1) is a key gene in plant defense response. In this study, the function of Oryza sativa SARD1 (OsSARD1) was investigated after exposure of seeds/plants to ionizing radiation, jasmonic acid (JA) or salicylic acid (SA).
Rice seeds exposed to two types of ionizing radiations (gamma ray [GR] and ion beam [IB]) were analyzed by quantitative reverse transcription PCR (qRT-PCR) to identify the genes that are altered in response to ionizing radiation. Then, OsSARD1-overexpressing homozygous Arabidopsis plants were generated to assess the effects of OsSARD1 in the response to irradiation. The phenotypes of these transgenic plants, as well as control plants, were monitored after GR irradiation at doses of 200 and 300 Gray (Gy).
The OsSARD1 transcript was strongly downregulated after exposure to GR and IB irradiation. Previous phylogenetic analysis showed that the Arabidopsis SARD1 (AtSARD1) protein is closely related to Arabidopsis calmodulin-binding protein 60g (AtCBP60g), which is known to be required for activation of SA biosynthesis. In this study, phylogenetic analysis showed that OsSARD1 was grouped with AtSARD1. The OsSARD1 gene was induced after exposure to SA and JA. The biological phenotype of OsSARD1-overexpressing Arabidopsis plants was examined. OsSARD1-overexpressing plants displayed resistance to GR; in comparison with wild-type plants, the height and weight of OsSARD1-overexpressing plants were significantly greater after GR irradiation. In addition, OsSARD1 protein was abundantly accumulated in the nucleus.
The results indicate that OsSARD1 plays an important role in the regulation of the defense responses to GR and IB irradiation and exhibits phytohormone induced expression.
暴露于电离辐射通过调节响应基因的表达诱导植物防御。系统获得性抗性缺陷1（SARD1）是植物防御反应中的关键基因。在本研究中，对种子/植株进行电离辐射、茉莉酸（JA）或水杨酸（SA）处理后，研究了水稻SARD1（OsSARD1）的功能。
通过定量逆转录PCR（qRT-PCR）分析暴露于两种电离辐射（γ射线[GR]和离子束[IB]）的水稻种子，以鉴定响应电离辐射而改变的基因。然后，构建过表达OsSARD1的纯合拟南芥植株，以评估OsSARD1在辐射响应中的作用。对这些转基因植株以及对照植株在200和300戈瑞（Gy）剂量的GR照射后的表型进行监测。
暴露于GR和IB辐射后，OsSARD1转录本强烈下调。先前的系统发育分析表明，拟南芥SARD1（AtSARD1）蛋白与拟南芥钙调蛋白结合蛋白60g（AtCBP60g）密切相关，已知AtCBP60g是SA生物合成激活所必需的。在本研究中，系统发育分析表明OsSARD1与AtSARD1归为一组。暴露于SA和JA后，OsSARD1基因被诱导。检测了过表达OsSARD1的拟南芥植株的生物学表型。过表达OsSARD1的植株对GR具有抗性；与野生型植株相比，GR照射后过表达OsSARD1的植株的高度和重量显著增加。此外，OsSARD1蛋白在细胞核中大量积累。
结果表明，OsSARD1在调节对GR和IB辐射的防御反应中起重要作用，并表现出植物激素诱导表达。
