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Zinc Finger Protein STOP1 Is Critical for Proton Tolerance in Arabidopsis and Coregulates a Key Gene in Aluminum Tolerance
Satoshi Iuchi, Hiroyuki Koyama, Atsuko Iuchi, Yasufumi Kobayashi, Sadako Kitabayashi, Yuriko Kobayashi, Takashi Ikka, Takashi Hirayama, Kazuo Shinozaki and Masatomo Kobayashi
Proceedings of the National Academy of Sciences of the United States of America
Vol. 104, No. 23 (Jun. 5, 2007), pp. 9900-9905
Published by: National Academy of Sciences
Stable URL: http://www.jstor.org/stable/25427957
Page Count: 6
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Acid soil syndrome causes severe yield losses in various crop plants because of the rhizotoxicities of ions, such as aluminum (Al³⁺). Although protons (H⁺) could be also major rhizotoxicants in some soil types, molecular mechanisms of their tolerance have not been identified yet. One mutant that was hypersensitive to H⁺ rhizotoxicity was isolated from ethyl methanesulfonate mutagenized seeds, and a single recessive mutation was found on chromosome 1. Positional cloning followed by genomic sequence analysis revealed that a missense mutation in the zinc finger domain in a predicted Cys₂His₂-type zinc finger protein, namely sensitive to proton rhizotoxicity (STOP)1, is the cause of hypersensitivity to H⁺ rhizotoxicity. The STOP1 protein belongs to a functionally unidentified subfamily of zinc finger proteins, which consists of two members in Arabidopsis based on a Blast search. The stop1 mutation resulted in no effects on cadmium, copper, lanthanum, manganese and sodium chloride sensitivitities, whereas it caused hypersensitivity to Al³⁺ rhizotoxicity. This stop1 mutant lacked the induction of the AtALMT1 gene encoding a malate transporter, which is concomitant with Al-induced malate exudation. There was no induction of AtALMT1 by Al³⁺ treatment in the stop1 mutant. These results indicate that STOP1 plays a critical role in Arabidopsis tolerance to major stress factors in acid soils.
Proceedings of the National Academy of Sciences of the United States of America © 2007 National Academy of Sciences