A new transgenic rice line exhibiting enhanced ferric iron reduction and phytosiderophore production confers tolerance to low iron availability in calcareous soil.
A new transgenic rice line exhibiting enhanced ferric iron reduction and phytosiderophore production confers tolerance to low iron availability in calcareous soil.
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DOI：
10.1371/journal.pone.0173441
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发表时间：
2017
期刊：
影响因子：
3.7
通讯作者：
Nishizawa NK
中科院分区：
文献类型：
--
作者：
Masuda H;Shimochi E;Hamada T;Senoura T;Kobayashi T;Aung MS;Ishimaru Y;Ogo Y;Nakanishi H;Nishizawa NK
缺铁是一个严重的农业问题，特别是在石灰性土壤中，这是世界性分布。水稻植物通过OsIRT 1转运蛋白从土壤中吸收Fe（II）（策略I相关系统），也通过基于植物铁载体的系统（策略II系统）吸收Fe（III）。然而，水稻植株对低铁条件敏感，因为它们具有低的Fe（III）还原活性和低水平的植物铁载体分泌。以前，我们生产的转基因水稻植物表达突变重建酵母铁螯合还原酶，refre 1/372，OsIRT 1启动子的控制下。该转基因水稻表现出较高的铁（III）螯合还原酶活性和耐缺铁。此外，我们生产了过表达Fe缺乏诱导转录因子OsIRO 2的转基因水稻，OsIRO 2调节参与策略II Fe（III）吸收系统的各种基因的表达，包括OsNAS 1，OsNAAT 1，OsDMAS 1，OsYSL 15和TOM 1。该转基因水稻表现出提高的植物铁载体分泌能力和对缺铁的耐受性。在本研究中，获得了同时具有OsIRT 1启动子-refre 1/372和35 S启动子-OsIRO 2的转基因水稻（RI系），以增强策略I Fe（II）还原酶能力和策略II植物铁载体生产力。与非转基因株系和单独携带OsIRT 1启动子-refre 1/372或35 S启动子-OsIRO 2的株系相比，RI株系在石灰性土壤中生长的早期和中后期表现出对缺铁条件的耐受性增强。RI系也表现出比非转基因系高9倍的产量。此外，我们还成功地培育了耐缺铁的立杉稻，这是一种高生物量的饲料品种。总的来说，我们的研究结果表明，在石灰性土壤中，两个铁吸收系统的联合增强水稻是非常有效的，赋予耐受性低铁可用性。
Iron (Fe) deficiency is a critical agricultural problem, especially in calcareous soil, which is distributed worldwide. Rice plants take up Fe(II) from soil through a OsIRT1 transporter (Strategy I-related system) and also take up Fe(III) via a phytosiderophore-based system (Strategy II system). However, rice plants are susceptible to low-Fe conditions because they have low Fe(III) reduction activity and low-level phytosiderophore secretion. Previously, we produced transgenic rice plants expressing a mutationally reconstructed yeast ferric chelate reductase, refre1/372, under the control of the OsIRT1 promoter. This transgenic rice line exhibited higher Fe(III) chelate reductase activity and tolerance to Fe deficiency. In addition, we produced transgenic rice overexpressing the Fe deficiency-inducible transcription factor, OsIRO2, which regulates the expression of various genes involved in the strategy II Fe(III) uptake system, including OsNAS1, OsNAAT1, OsDMAS1, OsYSL15, and TOM1. This transgenic rice exhibited improved phytosiderophore secretion ability and tolerance to Fe deficiency. In the present research, transgenic rice plants that possess both the OsIRT1 promoter-refre1/372 and the 35S promoter-OsIRO2 (RI lines) were produced to enhance both Strategy I Fe(II) reductase ability and Strategy II phytosiderophore productivity. RI lines exhibited enhanced tolerance to Fe-deficient conditions at the early and middle-late stages of growth in calcareous soil, compared to both the non-transgenic line and lines harboring either OsIRT1 promoter-refre1/372 or 35S promoter-OsIRO2 alone. RI lines also exhibited a 9-fold higher yield than the non-transgenic line. Moreover, we successfully produced Fe-deficiency-tolerant Tachisugata rice, which is a high-biomass variety used as fodder. Collectively, our results demonstrate that combined enhancement of two Fe uptake systems in rice is highly effective in conferring tolerance to low Fe availability in calcareous soil.