Cell-Type Specificity of the Expression of Os BOR1, a Rice Efflux Boron Transporter Gene, Is Regulated in Response to Boron Availability for Efficient Boron Uptake and Xylem Loading

We describe a boron (B) transporter, Os BOR1, in rice (Oryza sativa). Os BOR1 is a plasma membrane-localized efflux transporter of B and is required for normal growth of rice plants under conditions of limited B supply (referred to as -B). Disruption of Os BOR1 reduced B uptake and xylem loading of...

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Published inThe Plant cell Vol. 19; no. 8; pp. 2624 - 2635
Main Authors Nakagawa, Yuko, Hanaoka, Hideki, Kobayashi, Masaharu, Miyoshi, Kazumaru, Miwa, Kyoko, Fujiwara, Toru
Format Journal Article
LanguageEnglish
Published United States American Society of Plant Biologists 01.08.2007
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Summary:We describe a boron (B) transporter, Os BOR1, in rice (Oryza sativa). Os BOR1 is a plasma membrane-localized efflux transporter of B and is required for normal growth of rice plants under conditions of limited B supply (referred to as -B). Disruption of Os BOR1 reduced B uptake and xylem loading of B. The accumulation of Os BOR1 transcripts was higher in roots than that in shoots and was not affected by B deprivation; however, Os BOR1 was detected in the roots of wild-type plants under -B conditions, but not under normal conditions, suggesting regulation of protein accumulation in response to B nutrition. Interestingly, tissue specificity of Os BOR1 expression is affected by B treatment. Transgenic rice plants containing an Os BOR1 promoter-β-glucuronidase (GUS) fusion construct grown with a normal B supply showed the strongest GUS activity in the steles, whereas after 3 d of -B treatment, GUS activity was elevated in the exodermis. After 6 d of -B treatment, GUS activity was again strong in the stele. Our results demonstrate that Os BOR1 is required both for efficient B uptake and for xylem loading of B. Possible roles of the temporal changes in tissue-specific patterns of Os BOR1 expression in response to B condition are discussed.
Bibliography:http://www.plantcell.org/
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The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantcell.org) is: Toru Fujiwara (atorufu@mail.ecc.u-tokyo.ac.jp).
Current address: Iwate Biotechnology Research Center, Narita, Kitakami-shi, Iwate 024-0003, Japan.
www.plantcell.org/cgi/doi/10.1105/tpc.106.049015
Address correspondence to atorufu@mail.ecc.u-tokyo.ac.jp.
ISSN:1040-4651
1532-298X
DOI:10.1105/tpc.106.049015