不同空间辐射品质诱发的水稻生物学效应及其对基因组稳定影响的机制研究

At present, space radiation damage prediction has not made significant progress, which is mainly due to the complexity of space radiation environment and the existence of microgravity and other factors. In addition, the ground experiment can not fully simulate the real space radiation environment, which also restricts the progress of related research. With the development of high throughput detection and big-data analysis technologies, it may be an important breakthrough to solve the above problem by using the method of system theory to analyze the space radiation factors and the corresponding mechanisms of biological effects. This project integrated the radiation detectors with positioning function and seeds of rice (Oryza sativa japonica) into the biostacks, which were put into the SJ-10 recoverable satellite. After 12.5 days flight, we can obtain the spatial radiation quality and the characteristic data of rice from macro to micro. The project intends to use the data association and mining and other analytical techniques to study the biological effects of space radiation on rice at multiple scales, including phenotypic changes (such as plant height and root length, etc.), cytological damage (e. g., chromosomal aberration, etc.), and “omic” variation (such as functional genomics, proteomics and methylation sequencings, etc.) to reveal the characteristics of biological effects induced by different space radiation qualities, to mine the molecular markers of radiation sensitivity in space and study their regulatory functions, and to explore the characteristics of endogenous ROS induced by different space radiation qualities and their effects on genomic instability.

空间辐射损伤预警目前仍未获得根本性进展，这主要源于空间辐射环境的复杂性以及微重力等因素的存在。由于地基实验无法完全模拟真实的空间辐射环境，这也制约了相关研究的进展。伴随高通量检测和大数据分析技术的发展，应用系统论的方法挖掘空间辐射诱因和生物学效应机制可能成为解决上述问题的一个重要突破口。本研究集成具有定位功能的辐射探测片和水稻种子组成的生物堆叠经历了“实践十号”返回式卫星12.5天的飞行。卫星返回后，获取空间辐射品质和水稻从宏观到微观等不同层次上的特征数据。项目拟利用数据挖掘和关联等技术，研究空间辐射在多尺度下的生物学效应，包括表型变化（株高、根长等）、细胞学损伤（染色体畸变等）、以及“组学”变化（功能基因组学、蛋白质组及甲基化测序等）等，揭示空间辐射品质诱发的生物学效应特征，挖掘空间辐射敏感的分子标志物并研究其调控功能，探索不同空间辐射品质诱发內源性ROS的特征及其对基因组不稳定的影响。

空间环境诱发了机体慢性损伤效应，但其诱因及其生物学效应机制仍然不清楚。由于空间是一个存在各种辐射粒子并伴有微重力的特殊环境，特别目前的研究特别缺乏对空间高能粒子诱发生物学效应的认识，对于空间辐射损伤的评估仍然存在着超过400%以上的不确定性。本研究建立了对水稻种子胚部进行空间高能重离子定量获取技术，并利用大数据挖掘和互作模型等分析方法研究了被不同LET值重离子诱发的慢性损伤的分子机制。.结果表明空间高能重离子击中的水稻种子产生了近20%的致死率，存活的植株超过80%的比例出现了分蘖数的显著下降，并诱发根尖的H2O2的积累。内源性ROS的产生、传递和抗氧化酶基因表达被诱导，进而引起了一系列参与核酸和氨基酸等代谢相关基因的大量表达，变化基因的数量呈现类似RBE-LET依赖的变化特征。 LET值在60-150KeV/μm范围的重离子是最有效调控代谢功能的阈值，而被大于150 KeV/μm重离子击中时机体的反应能力下降。这些过程是由OsDRM2, OsOCL3b, OsAGO1a, OsRDR6 和OsDCL4甲基化转移酶对相关功能基因的甲基化水平修饰而调控的。二萜和类固醇生物合成是参与调控的关键通路。利用蛋白互作网络分析具有空间高能重离子LET值依赖表达的蛋白是氧化磷酸化激酶和热休克蛋白，为进一步建立空间辐射风险预警模型提供了分子标志物。