We report, in Arabidopsis thaliana plants, the effect of neutron irradiation on the transcription of a set of genes belonging to different physiological groups: auxin action, senescence, oxidative stress, and some aspects of photosynthesis. The results indicated that, in the wild-types, the effect on the ARF1, ARF2, and 19 genes was of down-regulation, whereas of the tested AUX/IAA only AUX/IAA7 showed up-regulation. Different results were obtained as regards the irradiation of the auxin transport mutants aux1 and eir1, because in these cases the ARF genes were up-regulated, whereas AUX/IAA7 was down-regulated in eir1. On the other hand, the senescence activated genes SAG12 and SAG13, and those connected to oxidative stress were up-regulated in the wild-type, but down-regulated in aux1. The gene CAB1, connected to photosynthesis, was also down-regulated in the wild-type, but up-regulated in aux1. Gene expression recovered in many cases almost to the initial condition in a time lapse of 24 hours, even though some effect persisted for a longer time. In particular, the state of juvenility of arf2 was extended by irradiation, whereas, in all the other cases, senescence was accelerated. The research indicates that through mutant selection or genetic engineering a true possibility exists of producing organism more suitable for life in space.