Zinc localization and speciation in rice grain under variable soil zinc deficiency
Zinc localization and speciation in rice grain under variable soil zinc deficiency
复制标题
不同土壤缺锌条件下水稻籽粒锌的定位和形态
DOI：
10.1007/s11104-023-06140-1
复制
发表时间：
2023-07
期刊：
影响因子：
4.9
通讯作者：
Yating Shen;Elizabeth G Wiita;A. Nghiem;J. Liu;E. Haque;R. Austin;Chheng Y. Seng;K. Phan;Yanjia Zheng;B. Bostick
中科院分区：
文献类型：
--
作者：
Yating Shen;Elizabeth G Wiita;A. Nghiem;J. Liu;E. Haque;R. Austin;Chheng Y. Seng;K. Phan;Yanjia Zheng;B. Bostick
背景和目的大米约占人类消耗的卡路里的20%。锌（Zn）等必需营养素对水稻生长和以水稻为主食的人群至关重要。没有行之有效的学习方法。因此，我们对稻谷中锌的化学形式缺乏清晰的认识。此外，我们还不了解土壤中广泛和可变的锌缺乏对锌形态的影响，以及在较小程度上对谷物中锌浓度的影响。方法采用同步加速器微探针x射线荧光（µ-XRF）和扩展x射线吸收精细结构光谱（EXAFS）分析柬埔寨大米的成分和Zn形态。我们开发了一种基于锌在特征键长上与氧和硫的配位数来量化不同配合物中锌种类的方法。结果糙米籽粒锌含量在15 ~ 30 mg kg−1之间，与土壤锌有效性无关。稻谷中72%-90%的锌以植酸锌的形式存在，通常不具有生物可利用性，而少量的锌以不稳定的烟胺配合物、锌矿物如znco3或硫醇结合。结论缺锌对水稻籽粒锌形成的影响大于以往的认识。水稻中大部分锌与植酸配合物结合。在缺锌土壤中，植酸锌络合物的浓度和比例都较高，这与缺锌土壤中植酸锌的产量增加一致。植酸盐一般不为人类生物利用，因此土壤锌肥力低不仅会影响粮食产量，还会降低粮食锌对人类消费者的生物利用比例。在缺锌环境中富集植酸锌对人体生物利用度和锌缺乏症的潜在影响有待进一步研究。
Background and aimsRice accounts for around 20% of the calories consumed by humans. Essential nutrients like zinc (Zn) are crucial for rice growth and for populations relying on rice as a staple food. No well-established study method exists. As a result, we a lack a clear picture of the chemical forms of zinc in rice grain. Furthermore, we do not understand the effects of widespread and variable zinc deficiency in soils on the Zn speciation, and to a lesser extent, its concentration, in grain.MethodsThe composition and Zn speciation of Cambodian rice grain is analyzed using synchrotron-based microprobe X-ray fluorescence (µ-XRF) and extended X-ray absorption fine-structure spectroscopy (EXAFS). We developed a method to quantify Zn species in different complexes based on the coordination numbers of Zn to oxygen and sulfur at characteristic bond lengths.ResultsZn levels in brown rice grain ranged between 15–30 mg kg−1and were not correlated to Zn availability in soils. 72%-90% of Zn in rice grains is present as Zn-phytate, generally not bioavailable, while smaller quantities of Zn are bound as labile nicotianamine complexes, Zn minerals like ZnCO3or thiols.ConclusionZn speciation in rice grain is affected by Zn deficiency more than previously recognized. A majority of Zn was bound in phytate complexes in rice grain. Zinc phytate complexes were found in higher concentrations and also in higher proportions, in Zn-deficient soils, consistent with increased phytate production under Zn deficiency. Phytates are generally not bioavailable to humans, so low soil Zn fertility may not only impact grain yields, but also decrease the fraction of grain Zn bioavailable to human consumers. The potential impact of abundant Zn-phytate in environments deficient in Zn on human bioavailability and Zn deficiency requires additional research.