Unraveling low-level gamma radiation-responsive changes in expression of early and late genes in leaves of rice seedlings at litate Village, Fukushima

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

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)

Abstract

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 μSv 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 × 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.

Original languageEnglish
Pages (from-to)723-738
Number of pages16
JournalJournal of Heredity
Volume105
Issue number5
DOIs
Publication statusPublished - 2014

Keywords

  • DNA repair
  • Gamma radiation
  • Oryza sativa
  • OsPCNA
  • Seedling leaf
  • Stress response

ASJC Scopus subject areas

  • Biotechnology
  • Molecular Biology
  • Genetics
  • Genetics(clinical)

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