Agricultural Biotechnology Research Center, Academia Sinica, Taipei, Taiwan.
Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica and National Chung Hsing University, Taipei, Taiwan.
Plant Biotechnol J. 2020 May;18(5):1200-1210. doi: 10.1111/pbi.13285. Epub 2019 Nov 20.
One of the goals of biofortification is to generate iron-enriched crops to combat growth and developmental defects especially iron (Fe) deficiency anaemia. Fe-fortification of food is challenging because soluble Fe is unstable and insoluble Fe is nonbioavailable. Genetic engineering is an alternative approach for Fe-biofortification, but so far strategies to increase Fe content have only encompassed a few genes with limited success. In this study, we demonstrate that the ethyl methanesulfonate (EMS) mutant, iron deficiency tolerant1 (idt1), can accumulate 4-7 times higher amounts of Fe than the wild type in roots, shoots and seeds, and exhibits the metal tolerance and iron accumulation (Metina) phenotype in Arabidopsis. Fe-regulated protein stability and nuclear localisation of the upstream transcriptional regulator bHLH34 were uncovered. The C to T transition mutation resulting in substitution of alanine to valine at amino acid position 320 of bHLH34 (designated as IDT1 ) in a conserved motif among mono- and dicots was found to be responsible for a dominant phenotype that possesses constitutive activation of the Fe regulatory pathway. Overexpression of IDT1 in Arabidopsis and tobacco led to the Metina phenotype; a phenotype that has escalated specificity towards optimising Fe homeostasis and may be useful in Fe-biofortification. Knowledge of the high tolerance and accumulation of heavy metals of this mutant can aid the development of tools for phytoremediation of contaminants.
生物强化的目标之一是培育富含铁的作物，以防治生长和发育缺陷，特别是缺铁性贫血。食物铁强化具有挑战性，因为可溶性铁不稳定，而不溶性铁无法被生物利用。遗传工程是铁生物强化的一种替代方法，但迄今为止，增加铁含量的策略仅涵盖了少数几个基因，成功有限。在本研究中，我们证明了乙基磺酸甲酯（EMS）突变体缺铁耐受 1（idt1）可以在根、茎和种子中积累比野生型高 4-7 倍的铁，并且在拟南芥中表现出金属耐受性和铁积累（Metina）表型。揭示了铁调节蛋白稳定性和上游转录调节因子 bHLH34 的核定位。在单双子叶植物保守基序中，bHLH34 第 320 位氨基酸由丙氨酸突变为缬氨酸（命名为 IDT1），导致 C 到 T 的转换突变，被认为是导致显性表型的原因，该表型具有铁调节途径的组成性激活。IDT1 在拟南芥和烟草中的过表达导致了 Metina 表型；该表型对优化铁稳态的特异性增强，可能在铁生物强化中有用。了解该突变体对重金属的高耐受性和积累能力，可以为植物修复污染物的工具的开发提供帮助。
