title: Effect of modeled microgravity on radiation-induced adaptive response of root growth in Arabidopsis thaliana.
abstract: Space particles have an inevitable impact on organisms during space missions; radio-adaptive response (RAR) is a critical radiation effect due to both low-dose background and sudden high-dose radiation exposure during solar storms. Although it is relevant to consider RAR within the context of microgravity, another major space environmental factor, there is no existing evidence as to its effects on RAR. In the present study, we established an experimental method for detecting the effects of gamma-irradiation on the primary root growth of Arabidopsis thaliana, in which RAR of root growth was significantly induced by several dose combinations. Microgravity was simulated using a two-dimensional rotation clinostat. It was shown that RAR of root growth was significantly inhibited under the modeled microgravity condition, and was absent in pgm-1 plants that had impaired gravity sensing in root tips. These results suggest that RAR could be modulated in microgravity. Time course analysis showed that microgravity affected either the development of radio-resistance induced by priming irradiation, or the responses of plants to challenging irradiation. After treatment with the modeled microgravity, attenuation in priming irradiation-induced expressions of DNA repair genes (AtKu70 and AtRAD54), and reduced DNA repair efficiency in response to challenging irradiation were observed. In plant roots, the polar transportation of the phytohormone auxin is regulated by gravity, and treatment with an exogenous auxin (indole-3-acetic acid) prevented the induction of RAR of root growth, suggesting that auxin might play a regulatory role in the interaction between microgravity and RAR of root growth.
authors.affiliation: Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, PR China; Key Laboratory of Environmental Toxicology and Pollution Control Technology of Anhui Province, PR China; Institute of Technical Biology and Agriculture Engineering, Chinese Academy of Sciences, 350 Shushanhu Road, Hefei 230031, PR China; University of Science and Technology of China, Hefei 230026, PR China.
authors.forename: Chenguang
authors.initials: C
authors.lastname: Deng
authors.affiliation: Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, PR China; Key Laboratory of Environmental Toxicology and Pollution Control Technology of Anhui Province, PR China; Institute of Technical Biology and Agriculture Engineering, Chinese Academy of Sciences, 350 Shushanhu Road, Hefei 230031, PR China.
authors.forename: Ting
authors.initials: T
authors.lastname: Wang
authors.affiliation: Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, PR China; Key Laboratory of Environmental Toxicology and Pollution Control Technology of Anhui Province, PR China; Institute of Technical Biology and Agriculture Engineering, Chinese Academy of Sciences, 350 Shushanhu Road, Hefei 230031, PR China; University of Science and Technology of China, Hefei 230026, PR China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Wu
authors.affiliation: Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, PR China; Key Laboratory of Environmental Toxicology and Pollution Control Technology of Anhui Province, PR China; Institute of Technical Biology and Agriculture Engineering, Chinese Academy of Sciences, 350 Shushanhu Road, Hefei 230031, PR China.
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.affiliation: China Space Molecular Biological Lab, China Academy of Space Technology, Beijing 100086, PR China.
authors.forename: Huasheng
authors.initials: H
authors.lastname: Li
authors.affiliation: China Space Molecular Biological Lab, China Academy of Space Technology, Beijing 100086, PR China.
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.affiliation: Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, PR China; Key Laboratory of Environmental Toxicology and Pollution Control Technology of Anhui Province, PR China; Institute of Technical Biology and Agriculture Engineering, Chinese Academy of Sciences, 350 Shushanhu Road, Hefei 230031, PR China.
authors.forename: Lijun
authors.initials: L
authors.lastname: Wu
authors.affiliation: China Space Molecular Biological Lab, China Academy of Space Technology, Beijing 100086, PR China. Electronic address: lujinying2001@sina.com.
authors.forename: Jinying
authors.initials: J
authors.lastname: Lu
authors.affiliation: Key Laboratory of Ion Beam Bioengineering, Hefei Institutes of Physical Science, Chinese Academy of Sciences, PR China; Key Laboratory of Environmental Toxicology and Pollution Control Technology of Anhui Province, PR China; Institute of Technical Biology and Agriculture Engineering, Chinese Academy of Sciences, 350 Shushanhu Road, Hefei 230031, PR China. Electronic address: bianpo@ipp.ac.cn.
authors.forename: Po
authors.initials: P
authors.lastname: Bian
mesh_terms: D017360:Arabidopsis / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000235:genetics; D004260:DNA Repair / Q000187:drug effects / Q000528:radiation effects; D005720:Gamma Rays; D006112:Gravitation; D007210:Indoleacetic Acids / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology; D018517:Plant Roots / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects; D013026:Space Flight; D018474:Weightlessness Simulation
chemical_list: D029681:Arabidopsis Proteins; D007210:Indoleacetic Acids; D010937:Plant Growth Regulators
keywords: Arabidopsis thaliana; Auxin; DNA repair pathway; Modeled microgravity; Radio-adaptive response; Root growth