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Phosphorus toxicity disrupts Rubisco activation and reactive oxygen species defense systems by phytic acid accumulation in leaves
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  • Daisuke Takagi,
  • Atsuko Miyagi,
  • Youshi Tazoe,
  • Mao Suganami,
  • Maki Kawai-Yamada,
  • Akihiro Ueda,
  • Yuji Suzuki,
  • Ko Noguchi,
  • Naoki Hirotsu,
  • Amane Makino
Daisuke Takagi
Tohoku University
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Atsuko Miyagi
Saitama Daigaku
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Youshi Tazoe
Tohoku University
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Mao Suganami
Tohoku University
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Maki Kawai-Yamada
Saitama University
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Akihiro Ueda
Hiroshima University
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Yuji Suzuki
Iwate University
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Ko Noguchi
Tokyo Yakka Daigaku Seimei Kagakubu Daigakuin Seimei Kagaku Kenkyuka
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Naoki Hirotsu
Toyo University
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Amane Makino
Tohoku University
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Abstract

Phosphorus (P) is one of the essential mineral nutrients for plants. Nevertheless, large amounts of accumulated P easily wither whole plants, and this phenomenon is termed as P toxicity. For improving P-use efficiency, to overcome P toxicity is necessary for plant growth. However, the detailed mechanisms underlying P toxicity in plants have not yet been elucidated. In this study, we aimed to investigate the molecular mechanism of P toxicity in rice. We found that, under excessive inorganic-P (Pi) application conditions, Rubisco activation decreased and photosynthesis was inhibited, leading to lipid-peroxidation. Although the defense systems against reactive oxygen species accumulation were activated under excessive Pi application conditions, the Cu/Zn-type superoxide dismutase activity was inhibited. A metabolic analysis revealed that excess Pi application led to an increase in the cytosolic sugar-phosphate content, and activation of phytic acid synthesis. These conditions induced mRNA expressions of the genes that are activated under metal-deficiency conditions, although metals were rather accumulated. These results suggested that P toxicity is triggered by the attenuation of both photosynthesis, and metal availability within cells mediated by phytic acid accumulation. Here, we discuss the whole phenomenon of P toxicity, beginning from the accumulation of Pi within cells to death in plants.

Peer review status:UNDER REVIEW

29 Jan 2020Submitted to Plant, Cell & Environment
29 Jan 2020Assigned to Editor
29 Jan 2020Submission Checks Completed
31 Jan 2020Reviewer(s) Assigned
21 Feb 2020Review(s) Completed, Editorial Evaluation Pending