title: Biological effects of protons targeted to different ranges in Arabidopsis seeds.
abstract: OBJECTIVE
  To investigate the biological effects of radiation damage induced at different depths of a plant seed and to investigate the difference in radiation response between dry seeds and water-imbibed seeds to the same type of radiation.
  
  
  METHODS
  Arabidopsis seeds of the wild-type Columbia ecotype were used in our experiments. Dry or water-imbibed Arabidopsis seeds were irradiated with 1.1 MeV, 2.6 MeV or 6.5 MeV protons (H+). For comparison, 30 keV nitrogen ions (N+) were also used to irradiate dry Arabidopsis seeds. The germination and survival rates of the seeds were measured after each irradiation.
  
  
  RESULTS
  After irradiation with 2.6 MeV H+ and 6.5 MeV H+, the fluence-response curves for germination and survival had distinct shoulders and then survival was reduced rapidly with increasing fluence. 2.6 MeV H+ was more effective than 6.5 MeV H+ in inhibiting germination and survival and water-imbibed seeds were more sensitive to the 6.5 MeV H+ irradiation than dry seeds. For 1.1 MeV H+ the germination and survival rates were reduced gradually and an intermediate plateau emerged for germination, which was similar to that observed for survival following 30 keV N+ irradiation. One of the key morphologic malformations, the multi-SAM (shoot apical meristem), was observed both for dry and water-imbibed seeds after all proton irradiations and for the dry seeds after 30 keV N+ irradiation.
  
  
  CONCLUSIONS
  Radiation-induced damage produced at different ranges in Arabidopsis seeds results in different fluence-response curves with water-imbibed seeds being more sensitive to proton irradiation than dry seeds. As well as the shoot apical meristem (SAM) being the primary target for irradiation, there exists a secondary target around the SAM that also contributes to the radiation response.
authors: Key Laboratory of Heavy Ion Physics, MOE, Peking University, Beijing, P R China.
authors: H L
authors: HL
authors: Qin
authors: Y G
authors: YG
authors: Wang
authors: J M
authors: JM
authors: Xue
authors: Q
authors: Q
authors: Miao
authors: L
authors: L
authors: Ma
authors: T
authors: T
authors: Mei
authors: W M
authors: WM
authors: Zhang
authors: W
authors: W
authors: Guo
authors: J Y
authors: JY
authors: Wang
authors: H Y
authors: HY
authors: Gu
mesh_terms: D017360:Arabidopsis / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D004307:Dose-Response Relationship, Radiation; D018525:Germination / Q000528:radiation effects; D020450:Heavy Ions; D018499:Linear Energy Transfer; D009584:Nitrogen; D011522:Protons; D012639:Seeds / Q000254:growth & development / Q000378:metabolism / Q000528:radiation effects*; D016019:Survival Analysis; D014867:Water / Q000378:metabolism
chemical_list: D011522:Protons; D014867:Water; D009584:Nitrogen