?生物學(xué)家了解到某些植物的種子是如何貯存鐵和貯藏的部位，這對(duì)于科學(xué)家致力提高植物中鐵的含量是一個(gè)重要發(fā)現(xiàn),。該研究有助于解決全球性的人類缺鐵癥和營養(yǎng)不良問題,。該結(jié)果于2006年11月2日發(fā)表在《ScienceExpress》上。
??研究發(fā)現(xiàn),，鐵貯存在擬南芥種子發(fā)育著的維管系統(tǒng)中,。特別地，鐵貯存在植物細(xì)胞液泡中,。研究也揭示了其定位依賴于VIT1蛋白,，該蛋白負(fù)責(zé)將鐵運(yùn)輸?shù)揭号荨?/p>
??“缺鐵癥是當(dāng)今世界上最常見的人類營養(yǎng)性病癥，全世界有30多億人患有此病,。”美國新罕布什爾州Dartmouth大學(xué)的Mary Lou Guerinot說,。
??“大多數(shù)病人依靠植物食譜來增加鐵，但植物含鐵量不高,，土壤中鐵的低利用率限制植物生長,。研究表明，液泡中鐵的儲(chǔ)存有希望增加種子中鐵的含量。營養(yǎng)豐富的種子有益于人類健康和農(nóng)業(yè)生產(chǎn)力,。”
??研究者把傳統(tǒng)的突變體分析（VIT1蛋白的開啟與關(guān)閉）和X-射線影像技術(shù)結(jié)合起來繪制出鐵定位于種子的圖譜,。Guerinot對(duì)此發(fā)現(xiàn)很驚訝，因?yàn)殛P(guān)于鐵的大多數(shù)研究集中于鐵蛋白的研究,。
??“該項(xiàng)目研究發(fā)現(xiàn),，利用遺傳學(xué)和三維X-射線熒光成像可以了解基因功能，鐵定位于種子特異部位的發(fā)現(xiàn)開啟了增加谷類和豆類重要營養(yǎng)物質(zhì)含量的可能性,。” Jane Silverthorne說,。
??該發(fā)現(xiàn)表明，除了鐵蛋白以外,，理解鐵是如何貯存在植物中是很有必要的,。研究者認(rèn)為液泡中貯存的鐵是幼苗發(fā)育中鐵的主要來源。VTI1不表達(dá)的幼苗由于鐵的限制生長不好,。
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.
