Heavy ion and cosmic radiation effects in different targets of the Arabidopsis seed

The seed embryo of Arabidopsis thaliana, the favorite plant of up-to-date molecular developmental biology, represents a valuable model system for space radiation research with heavy ions. For several years, densely ionizing particles have been available for basic studies in nuclear physics and radiation biology through special accelerators as well as through space flight missions. Because of the great variability of the available radiation spectra, the induced relative biological effect (RBE-value) has to be differentiated with respect to the effective charge (z) and the linear energy transfer (LET) deposited in a certain volume of matter, and to the biological targets which differ in size, structure and function. The results of comparative studies of 8 space flight experiments, here by example show increasing damage produced by single heavy ions and/or cosmic background radiation (protons, neutrons, X-rays). These results offer new prospects for molecular investigation of the RBE of heavy ions in space.