Iron accumulation does not parallel the high expression level of ferritin in transgenic rice seeds
Iron accumulation does not parallel the high expression level of ferritin in transgenic rice seeds
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DOI：
10.1007/s00425-005-1530-8
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发表时间：
2005-10-01
期刊：
影响因子：
4.3
通讯作者：
Takaiwa, F
中科院分区：
文献类型：
--
作者：
Qu, LQ;Yoshihara, T;Takaiwa, F
为了回答转基因水稻种子中铁的积累是否取决于外源大豆铁蛋白的表达水平的问题，我们通过在水稻种子贮藏谷蛋白基因启动子Glub-1和水稻种子贮藏球蛋白基因启动子GLb-1的控制下导入大豆铁蛋白SoyferH-1基因(Glub-1/SoyferH-1和GLb-1/SoyferH-1，DF系)和单独在GLB-1启动子控制下导入大豆H-1基因(GLB-1/SoyferH-1)，获得了两种铁蛋白高表达水稻品系。在这两个品系中，铁蛋白的表达都局限于胚乳中，蛋白质水平经Western印迹分析比之前报道的FK22(Glub-1/SoyferH-1，在Kitaake背景下)高出13倍；然而，这两个新品系的种子中的最大铁含量仅比FK22高约30%。转化子F和DF的最大含铁量约为非转化子的3倍。铁蛋白高表达品系叶片中铁的平均含量下降到未转化品系的一半以下，而植株生物量和种子产量与未转化品系差异不显著，说明铁在高表达水稻种子中的积累并不总是取决于外源铁蛋白的表达水平，而可能受到铁的吸收和运输的限制。其他二价金属(钙、镉、铜、镁、锰、锌)含量在所有转化系和非转化体之间没有明显差异。
To answer the question whether iron accumulation in transgenic rice seeds depends on the expression level of exogenous soybean ferritin, we generated two kinds of ferritin hyper-expressing rice lines by introducing soybean ferritin SoyferH-1 gene under the control of the rice seed storage glutelin gene promoter, GluB-1 and the rice seed storage globulin gene promoter, Glb-1, (GluB-1/SoyferH-1 and Glb-1/SoyferH-1, DF lines), and by introducing the SoyferH-1 gene under the control of Glb-1 promoter alone (Glb-1/SoyferH-1, OF lines). Ferritin expression was restricted to the endosperm in both lines and protein levels determined by western blot analysis were up to 13-fold higher than in a construct previously reported FK22 (GluB-1/SoyferH-1, in genetically Kitaake background); however, the maximum iron concentrations in seeds of both of the new lines were only about 30% higher than FK22. The maximum iron concentration in the OF and DF lines was about threefold higher than in the non-transformant. The mean Fe concentration in leaves of ferritin over-expressing lines decreased to less than half of the non-transformant while that the plant biomasses and seed yields of the ferritin-transformed lines were not significantly different from those of the non-transformant, suggesting that accumulation of Fe in seeds of hyper-expression ferritin rice did not always depend on the expression level of exogenous ferritin but may have been limited by Fe uptake and transport. No obvious differences were observed for other divalent-metal concentrations (Ca, Cd, Cu, Mg, Mn and Zn) in the seeds among all experimental lines and non-transformant.