Abstract
Native plants are continuously exposed to ionizing radiation in radiologically contaminated areas. For detection of biological responses of the plants to the continuous irradiation in the natural environment, radiation-induced gene expression was examined in a Japanese native conifer, Japanese cedar (Cryptomeria japonica). An initial screening of the transcripts from the plants by the HICEP (High Coverage Expression Profiling) analysis selected 53 transcripts that exhibited 3 times higher or lower expression levels after gamma ray exposure for 25 days at a dose rate of 100 mGy/day. Many of the transcripts showed homology to known coniferous ESTs, 17 % (17 out of 53) matched the EST sequences of Japanese cedar and 60 % (32 out of 53) were homologues to those of any coniferous plant species. Additionally, 58 % (31 out of 53) of the transcripts were homologous to the genes of a model plant arabidopsis, which enabled functional estimation of the transcripts. The transcripts were further analyzed for irradiation dependent expression patterns by the real time PCR method to be identified as the radiation responsive transcripts. Use of the transcripts as biomarkers for the radiation effects in Japanese cedar will be discussed.
