Unraveling Low-Level Gamma Radiation-Responsive Changes in Expression of Early and Late Genes in Leaves of Rice Seedlings at litate Village, Fukushima

作者：Hayashi Gohei; Shibato Junko; Imanaka Tetsuji; Cho Kyoungwon; Kubo Akihiro; Kikuchi Shoshi; Satoh Kouji; Kimura Shinzo; Ozawa Shoji; Fukutani Satoshi; Endo Satoru; Ichikawa Katsuki; Agrawal Ganesh Kumar; Shioda Seiji; Fukumoto Manabu; Rakwal Randeep^*

来源：Journal of Heredity, 2014, 105(5): 723-738.

DOI：10.1093/jhered/esu025

• DNA repair
• gamma radiation
• Oryza sativa
• OsPCNA
• seedling leaf
• stress response

In the summer of 2012, 1 year after the nuclear accident in March 2011 at the Fukushima Daiichi nuclear power plant, we examined the effects of gamma radiation on rice at a highly contaminated field of Iitate village in Fukushima, Japan. We investigated the morphological and molecular changes on healthy rice seedlings exposed to continuous low-dose gamma radiation up to 4 mu Sv h(-1), about 80 times higher than natural background level. After exposure to gamma rays, expression profiles of selected genes involved in DNA replication/repair, oxidative stress, photosynthesis, and defense/stress functions were examined by RT-PCR, which revealed their differential expression in leaves in a time-dependent manner over 3 days (6, 12, 24, 48, and 72 h). For example, OsPCNA mRNA rapidly increased at 6, 12, and 24 h, suggesting that rice cells responded to radiation stress by activating a gene involved in DNA repair mechanisms. At 72 h, genes related to the phenylpropanoid pathway (OsPAL2) and cell death (OsPR1oa) were strongly induced, indicating activation of defense/stress responses. We next profiled the transcriptome using a customized rice whole-genome 4 x 44K DNA microarray at early (6 h) and late (72 h) time periods. Low-level gamma radiation differentially regulated rice leaf gene expression (induced 4481 and suppressed 3740 at 6 h and induced 2291 and suppressed 1474 genes at 72 h) by at least 2-fold. Using the highly upregulated and downregulated gene list, MapMan bioinformatics tool generated diagrams of early and late pathways operating in cells responding to gamma ray exposure. An inventory of a large number of gamma radiation-responsive genes provides new information on novel regulatory processes in rice.

• 出版日期2014-10