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タイトル: Study of the molecular mechanisms of boron toxicity in plants : Characterization of Arabidopsis thaliana mutants hypersensitive to excess boron
その他のタイトル: 植物におけるホウ素毒性の分子機構の研究 : ホウ素過剰超感受性シロイヌナズナ変異株の解析
著者: Sakamoto, Takuya
著者(別言語): 坂本, 卓也
発行日: 2011年3月24日
抄録: The molecular mechanisms of boron (B) toxicity are not well-understood. In order to obtain insights into the molecular mechanisms of B toxicity, seven Arabidopsis thaliana mutants hypersensitive to excess B (heb) were studied. Through the analysis of the mutants, I first identified six genes involved in B toxicity-tolerance. These genes represent the first identification of genes essential for B toxicity-tolerance in plants. Boron (B) is an essential element for plants. It can also become toxic when it exists in soils at excessive levels. Limitation of crop yield and quality caused by B toxicity is an agricultural problem in the world especially in semi arid areas. To understand B toxicity mechanisms and breed excess-B tolerant crops, isolation of genes involved in B toxicity and/or tolerance has been attempted. Recently, overexpression of B transport molecules BOR4 and TIP5;1 were revealed to improve excess-B tolerance in plants, although the biological functions of these molecules in B toxicity have remained unclear. These studies established that regulations of molecules function in efflux and uptake of B are major mechanisms for excess-B tolerances in plants. On the other hand, at the molecular level, mechanisms of excess-B toxicity are still unknown. Other than B transport molecules, several A. thaliana proteins involved in transcription, RNA process and anti-oxidative system are shown to provide B tolerance to yeast. However, their functions in B toxicity-tolerance are not revealed yet. Moreover, it has not been elucidated whether these genes are essential for B toxicity-tolerance in plants. Isolation and identification of novel plant genes involved in B toxicity and/or tolerance is expected to provide us new insights into molecular mechanisms of B toxicity in plants. For this purpose, I focused on genetic approach using EMS mutagenized Arabidopsis thaliana (ectype Col-0). I studied seven recessive mutants, hypersensitive to excess B (heb). The heb mutants showed extremely shorter relative root length than the wild-type under the toxic B condition (3 mM boric acid), although they showed slightly reduced root elongation under the control condition (0.03 mM boric acid), indicating their hypersensitivity to excess B. In the present thesis, I identified the genes that are essential for B toxicity-tolerance in plants using the heb mutants and characterized their functions in B toxicity-tolerance. Through the analyses, I established new aspects of two protein complexes, condensin II and 26S proteasome.
内容記述: 報告番号: 甲26907 ; 学位授与年月日: 2011-03-24 ; 学位の種別: 課程博士 ; 学位の種類: 博士(農学) ; 学位記番号: 博農第3660号 ; 研究科・専攻: 農学生命科学研究科応用生命工学専攻
URI: http://hdl.handle.net/2261/51986
出現カテゴリ:021 博士論文
1160620 博士論文(応用生命工学専攻)

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