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Phytochelatin synthase Os PCS 1 plays a crucial role in reducing arsenic levels in rice grains
Author(s) -
Hayashi Shimpei,
Kuramata Masato,
Abe Tadashi,
Takagi Hiroki,
Ozawa Kenjirou,
Ishikawa Satoru
Publication year - 2017
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.13612
Subject(s) - biology , mutant , phytochelatin , arsenic , genetically modified rice , gene , cadmium , wild type , cloning (programming) , atp synthase , biochemistry , transgene , microbiology and biotechnology , botany , genetically modified crops , enzyme , glutathione , chemistry , organic chemistry , computer science , programming language
Summary Reduction of the level of arsenic (As) in rice grains is an important challenge for agriculture. A recent study reported that the Os ABCC 1 transporter prevents the accumulation of As in grains by sequestering As–phytochelatin complexes into vacuoles in the upper nodes. However, how phytochelatins are provided in response to As remains unclear. Here, we show that the phytochelatin synthase Os PCS 1 plays a crucial role in reducing As levels in rice grains. Using a forward genetic approach, we isolated two rice mutants ( has1 and has2 ) in which As levels were much higher in grains but significantly lower in node I compared with the wild type. Map‐based cloning identified the genes responsible as Os ABCC 1 in has1 and Os PCS 1 in has2 . The levels of As in grains and node I were similar between the two mutants, suggesting that Os ABCC 1 preferentially cooperates with Os PCS 1 to sequester As, although rice has another phytochelatin synthase, Os PCS 2. An in vitro phytochelatin synthesis assay indicated that Os PCS 1 was more sensitive to activation by As than by cadmium, whereas Os PCS 2 was more weakly activated by As than by cadmium. Transgenic plants highly expressing Os PCS 1 showed significantly lower As levels in grains than did wild‐type plants. Our results provide new knowledge of the relative contribution of rice PCS paralogs to As sequestration and suggest a good candidate tool to reduce As levels in rice grains.