?生物学家了解到某些植物的种子是如何贮存铁和贮藏的部位,这对于科学家致力提高植物中铁的含量是一个重要发现。该研究有助于解决全球性的人类缺铁症和营养不良问题。该结果于2006年11月2日发表在《ScienceExpress》上。
??研究发现,铁贮存在拟南芥种子发育着的维管系统中。特别地,铁贮存在植物细胞液泡中。研究也揭示了其定位依赖于VIT1蛋白,该蛋白负责将铁运输到液泡。
??“缺铁症是当今世界上最常见的人类营养性病症,全世界有30多亿人患有此病。”美国新罕布什尔州Dartmouth大学的Mary Lou Guerinot说。
??“大多数病人依靠植物食谱来增加铁,但植物含铁量不高,土壤中铁的低利用率限制植物生长。研究表明,液泡中铁的储存有希望增加种子中铁的含量。营养丰富的种子有益于人类健康和农业生产力。”
??研究者把传统的突变体分析(VIT1蛋白的开启与关闭)和X-射线影像技术结合起来绘制出铁定位于种子的图谱。Guerinot对此发现很惊讶,因为关于铁的大多数研究集中于铁蛋白的研究。
??“该项目研究发现,利用遗传学和三维X-射线荧光成像可以了解基因功能,铁定位于种子特异部位的发现开启了增加谷类和豆类重要营养物质含量的可能性。” Jane Silverthorne说。
??该发现表明,除了铁蛋白以外,理解铁是如何贮存在植物中是很有必要的。研究者认为液泡中贮存的铁是幼苗发育中铁的主要来源。VTI1不表达的幼苗由于铁的限制生长不好。
英文原文:
Dartmouth study contributes to research addressing malnutrition and iron deficiency
Dartmouth biologists are leading a research team that has learned where and how some plant seeds store iron, a valuable discovery for scientists working to improve the iron content of plants.This research helps address the worldwide issue of iron deficiency and malnutrition. Their findings were published online on Nov. 2 at ScienceExpress, the advance publication site for the journal Science.
The team found that iron is stored in the developing vascular system of the seed of Arabidopsis, a model plant used in research; in particular, iron is stored in the vacuole, a plant cell’s central storage site. The researchers also learned that this localization is dependent on a protein called VIT1, shown to transport iron into the vacuole.
Dartmouth Professor of Biological Sciences Mary Lou Guerinot, the principal investigator on the study, says, “Iron deficiency is the most common human nutritional disorder in the world today, afflicting more than three billion people worldwide. Most of these people rely on plants for their dietary iron. However, plants are not high in iron, and the limited availability of iron in the soil can limit plant growth. Our study certainly suggests that iron storage in the vacuole is a promising and, before now, largely unexplored target for increasing the iron content of seeds. Such nutrient-rich seed would benefit both human health and agricultural productivity.”
The researchers combined traditional mutant analysis (turning on and off the VIT1 protein) with a powerful X-ray imaging technique to create a map of where iron is localized in the seed. Guerinot was surprised by the finding because most studies on iron storage focus on the protein ferritin. This paper reveals how important it is to look beyond ferritin to understand how iron is stored by plants. The researchers say that their study suggests that the stored iron in the vacuole is an important source of iron for developing seedlings. Seedlings that do not express the VIT1 protein grow poorly when iron is limited.
“We have demonstrated the usefulness of synchrotron X-ray fluorescence microtomography to look inside a seed,” says Guerinot. “This technique is noninvasive and requires no sample preparation. We think our work will open the way for many more biologists to use this technique to examine the spatial distribution of metals in samples of interest.” The imaging was carried out at the Department of Energy’s National Synchrotron Light Source at Brookhaven National Laboratory.