Boonyaves Kulaporn, Gruissem Wilhelm, Bhullar Navreet K
Plant Biotechnology, Department of Biology, ETH Zurich (Swiss Federal Institute of Technology Zurich), Universitaetsstrasse 2, 8092, Zurich, Switzerland.
Plant Mol Biol. 2016 Feb;90(3):207-15. doi: 10.1007/s11103-015-0404-0. Epub 2015 Nov 11.
Rice is a staple food for over half of the world's population, but it contains only low amounts of bioavailable micronutrients for human nutrition. Consequently, micronutrient deficiency is a widespread health problem among people who depend primarily on rice as their staple food. Iron deficiency anemia is one of the most serious forms of malnutrition. Biofortification of rice grains for increased iron content is an effective strategy to reduce iron deficiency. Unlike other grass species, rice takes up iron as Fe(II) via the IRON REGULATED TRANSPORTER (IRT) in addition to Fe(III)-phytosiderophore chelates. We expressed Arabidopsis IRT1 (AtIRT1) under control of the Medicago sativa EARLY NODULIN 12B promoter in our previously developed high-iron NFP rice lines expressing NICOTIANAMINE SYNTHASE (AtNAS1) and FERRITIN. Transgenic rice lines expressing AtIRT1 alone had significant increases in iron and combined with NAS and FERRITIN increased iron to 9.6 µg/g DW in the polished grains that is 2.2-fold higher as compared to NFP lines. The grains of AtIRT1 lines also accumulated more copper and zinc but not manganese. Our results demonstrate that the concerted expression of AtIRT1, AtNAS1 and PvFERRITIN synergistically increases iron in both polished and unpolished rice grains. AtIRT1 is therefore a valuable transporter for iron biofortification programs when used in combination with other genes encoding iron transporters and/or storage proteins.
大米是世界上超过一半人口的主食，但它所含的可被人体吸收利用的微量营养素含量较低。因此，微量营养素缺乏是主要依赖大米为主食的人群中普遍存在的健康问题。缺铁性贫血是最严重的营养不良形式之一。通过生物强化提高稻米中铁含量是减少缺铁的有效策略。与其他禾本科植物不同，水稻除了通过铁载体螯合的Fe(III)吸收铁外，还通过铁调节转运蛋白（IRT）以Fe(II)的形式吸收铁。我们在之前培育的表达烟酰胺合酶（AtNAS1）和铁蛋白的高铁NFP水稻品系中，在苜蓿早期结瘤素12B启动子的控制下表达拟南芥IRT1（AtIRT1）。单独表达AtIRT1的转基因水稻品系铁含量显著增加，与NAS和铁蛋白共同表达时，精米中铁含量增加到9.6μg/g干重，比NFP品系高2.2倍。AtIRT1品系的谷粒还积累了更多的铜和锌，但没有积累更多的锰。我们的结果表明，AtIRT1、AtNAS1和菜豆铁蛋白的协同表达能协同增加糙米和精米中的铁含量。因此，当与其他编码铁转运蛋白和/或储存蛋白的基因联合使用时，AtIRT1是铁生物强化计划中一种有价值的转运蛋白。
