In the tetrapyrrole biosynthetic pathway of higher plants, 5-aminolevulinic acid （ALA） is metabolized by ALA dehydratase （ALAD）. Here, we isolated ALAD1 cDNA from common wheat （Triticum aestivum L.） and its dipl...In the tetrapyrrole biosynthetic pathway of higher plants, 5-aminolevulinic acid （ALA） is metabolized by ALA dehydratase （ALAD）. Here, we isolated ALAD1 cDNA from common wheat （Triticum aestivum L.） and its diploid progenitors, and produced transgenic tobacco plants expressing the wheat ALAD1 gene. The ALAD1 genes were highly conserved among wheat relatives, and three homoeologous loci of wheat ALAD1 （TaALAD1） were equally transcribed in common wheat. A transient expression assay of a TaALAD1-GFP （green fluorescent protein） fusion protein suggested that TaALAD1 is localized in chloroplasts. Overexpression of TaALAD1 in transgenic tobacco resulted in a significant increase in ALAD activity in leaves. Moreover, the transgenic tobacco showed vigorous growth and increased survival rate on medium containing ALA at herbicidal concentrations. These results indicate that wheat ALAD1 has catalytic activity in metabolizing ALA in plastids, and that ectopic expression of TaALAD1 in transgenic plants increases their tolerance to ALA application at high concentrations.展开更多
基金supported by grants from the Ministry of Education, Culture, Sports, Science and Technology of Japan (Grant-in-Aid for Scientific Research (B) No. 21380005Grant-in-Aid for Challenging Exploratory Research No. 23658010) to Shigeo Takumipartially supported by Special Coordination Funds for Promoting Science and Technology, Creation of Innovation Centers for Advanced Interdisciplinary Research Areas (Innovative Bioproduction Kobe), MEXT, Japan.
文摘In the tetrapyrrole biosynthetic pathway of higher plants, 5-aminolevulinic acid （ALA） is metabolized by ALA dehydratase （ALAD）. Here, we isolated ALAD1 cDNA from common wheat （Triticum aestivum L.） and its diploid progenitors, and produced transgenic tobacco plants expressing the wheat ALAD1 gene. The ALAD1 genes were highly conserved among wheat relatives, and three homoeologous loci of wheat ALAD1 （TaALAD1） were equally transcribed in common wheat. A transient expression assay of a TaALAD1-GFP （green fluorescent protein） fusion protein suggested that TaALAD1 is localized in chloroplasts. Overexpression of TaALAD1 in transgenic tobacco resulted in a significant increase in ALAD activity in leaves. Moreover, the transgenic tobacco showed vigorous growth and increased survival rate on medium containing ALA at herbicidal concentrations. These results indicate that wheat ALAD1 has catalytic activity in metabolizing ALA in plastids, and that ectopic expression of TaALAD1 in transgenic plants increases their tolerance to ALA application at high concentrations.
