国外研究

改善身体缺铁和锌的方法——吃米饭

作者: 来源:PLoS ONE 2018-03-07 我要评论( )

缺铁和缺锌影响着亚洲穷国成千上万的人。近日,澳大利亚植物功能基因组学中心(ACPFG)的科学家Alex Johnson宣布,他们已经在培育解决铁和锌缺乏症的水稻品种的征程中取得了一个突破

改善身体缺铁和锌的方法——吃米饭

上图:白色的稻米锌和铁的含量比较低( Shutterstock)

缺铁和缺锌影响着亚洲穷国成千上万的人。近日,澳大利亚植物功能基因组学中心(ACPFG)的科学家Alex Johnson宣布,他们已经在培育解决铁和锌缺乏症的水稻品种的征程中取得了一个突破进展,相关研究发表在《公共科学图书馆》(PLoS ONE)上。

新转基因水稻的含铁量是传统水稻的4倍以上,含锌量是传统水稻的两倍。“这种水稻是白米铁含量最高的(高达百万分之19)。我们还证明了铁存在于组成了白米的胚乳组织中,”Johnson说。这很重要,因为人们广泛食用白米。

“这个新的报告记载了增加水稻谷粒铁含量的一种方法的令人兴奋的早期结果,”部分资助了该研究的美国HarvestPlus组织的水稻作物研究组负责人Gerard Barry说。“碾米谷粒中的铁含量增加对于人类营养非常重要。”

促进生物强化食品研究的HarvestPlus组织通常把重点放在传统的植物育种方法上。但是很难通过传统育种方法实现水稻铁含量的增加,因为几乎没有铁含量更高的天然水稻品种用于这种育种过程。

Johnson及其研究组把重点放在了烟草胺上。这是一种在水稻中天然存在的物质,能帮助从土壤中吸收铁。在正常情况下,正是由于土壤铁含量低为水稻发出了信号,让水稻打开控制烟草胺制造的基因。这组科学家成功地让这些基因一直打开。

这种方法也增加了锌的含量。

Johnson说,由于烟草胺自然存在于水稻中,食用这种水稻不太可能有任何健康副作用。

但是他说在这种新型水稻释放供人类食用之前可能需要10年时间。因为需要用几个季节的时间进行大田评估,而且需要生物利用度研究,从而发现动物是否真正能吸收这些铁。

大田试验已经在位于菲律宾的国际水稻研究所(IRRI)开始。

原文摘要:

Constitutive Overexpression of the OsNAS Gene Family Reveals Single-Gene Strategies for Effective Iron- and Zinc-Biofortification of Rice Endosperm

Alexander A. T. Johnson1,2*, Bianca Kyriacou2,3, Damien L. Callahan4, Lorraine Carruthers2, James Stangoulis3, Enzo Lombi5, Mark Tester2

Background:Rice is the primary source of food for billions of people in developing countries, yet the commonly consumed polished grain contains insufficient levels of the key micronutrients iron (Fe), zinc (Zn) and Vitamin A to meet daily dietary requirements. Experts estimate that a rice-based diet should contain 14.5 µg g−1 Fe in endosperm, the main constituent of polished grain, but breeding programs have failed to achieve even half of that value. Transgenic efforts to increase the Fe concentration of rice endosperm include expression of ferritin genes, nicotianamine synthase genes (NAS) or ferritin in conjunction with NAS genes, with results ranging from two-fold increases via single-gene approaches to six-fold increases via multi-gene approaches, yet no approach has reported 14.5 µg g−1 Fe in endosperm.

Methodology/Principal Findings:Three populations of rice were generated to constitutively overexpress OsNAS1, OsNAS2 orOsNAS3, respectively. Nicotianamine, Fe and Zn concentrations were significantly increased in unpolished grain of all three of the overexpression populations, relative to controls, with the highest concentrations in the OsNAS2 and OsNAS3 overexpression populations. Selected lines from each population had at least 10 µg g−1 Fe in polished grain and two OsNAS2 overexpression lines had 14 and 19 µg g−1 Fe in polished grain, representing up to four-fold increases in Fe concentration. Two-fold increases of Zn concentration were also observed in the OsNAS2population. Synchrotron X-ray fluorescence spectroscopy demonstrated that OsNAS2overexpression leads to significant enrichment of Fe and Zn in phosphorus-free regions of rice endosperm.

Conclusions:The OsNAS genes, particularly OsNAS2, show enormous potential for Fe and Zn biofortification of rice endosperm. The results demonstrate that rice cultivars overexpressing single rice OsNASgenes could provide a sustainable and genetically simple solution to Fe and Zn deficiency disorders affecting billions of people throughout the world.

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改善身体缺铁和锌的方法——吃米饭,新转基因水

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