Centre for Carbohydrate Recognition and Signalling, Department of Molecular Biology, University of Aarhus, Aarhus, Denmark.
BMC Plant Biol. 2010 Feb 11;10:26. doi: 10.1186/1471-2229-10-26.
Iron is an important micronutrient for all living organisms. Almost 25% of the world population is affected by iron deficiency, a leading cause of anemia. In plants, iron deficiency leads to chlorosis and reduced yield. Both animals and plants may suffer from iron deficiency when their diet or environment lacks bioavailable iron. A sustainable way to reduce iron malnutrition in humans is to develop staple crops with increased content of bioavailable iron. Knowledge of where and how iron accumulates in seeds of crop plants will increase the understanding of plant iron metabolism and will assist in the production of staples with increased bioavailable iron.
Here we reveal the distribution of iron in seeds of three Phaseolus species including thirteen genotypes of P. vulgaris, P. coccineus, and P. lunatus. We showed that high concentrations of iron accumulate in cells surrounding the provascular tissue of P. vulgaris and P. coccineus seeds. Using the Perls' Prussian blue method, we were able to detect iron in the cytoplasm of epidermal cells, cells near the epidermis, and cells surrounding the provascular tissue. In contrast, the protein ferritin that has been suggested as the major iron storage protein in legumes was only detected in the amyloplasts of the seed embryo. Using the non-destructive micro-PIXE (Particle Induced X-ray Emission) technique we show that the tissue in the proximity of the provascular bundles holds up to 500 microg g(-1) of iron, depending on the genotype. In contrast to P. vulgaris and P. coccineus, we did not observe iron accumulation in the cells surrounding the provascular tissues of P. lunatus cotyledons. A novel iron-rich genotype, NUA35, with a high concentration of iron both in the seed coat and cotyledons was bred from a cross between an Andean and a Mesoamerican genotype.
The presented results emphasize the importance of complementing research in model organisms with analysis in crop plants and they suggest that iron distribution criteria should be integrated into selection strategies for bean biofortification.
铁是所有生物的重要微量元素。全球近 25%的人口受到缺铁的影响，这是导致贫血的主要原因。在植物中，缺铁会导致黄化和减产。当动物和植物的饮食或环境缺乏可利用的铁时，它们可能会遭受缺铁。减少人类铁营养不良的可持续方法是开发富含可利用铁的主食作物。了解铁在作物种子中的积累位置和方式将增加对植物铁代谢的理解，并有助于生产富含可利用铁的主食。
本文揭示了三个菜豆属物种种子中铁的分布情况，包括十三份普通菜豆、多花菜豆和利马豆的基因型。我们发现，铁在普通菜豆和多花菜豆种子的维管束周围细胞中积累浓度较高。利用普鲁士蓝法，我们能够在表皮细胞、靠近表皮的细胞和维管束周围的细胞的细胞质中检测到铁。相比之下，铁蛋白被认为是豆科植物中主要的铁储存蛋白，仅在种子胚的淀粉体中被检测到。利用无损性微束 PIXE（粒子诱导 X 射线发射）技术，我们发现，靠近维管束束的组织中铁的含量高达 500μg g(-1)，具体取决于基因型。与普通菜豆和多花菜豆不同，我们没有观察到利马豆子叶维管束周围细胞中铁的积累。一个新的富铁基因型 NUA35，其种子种皮和子叶中的铁浓度都很高，是从安第斯和中美洲基因型杂交中选育出来的。
本研究结果强调了在模式生物研究中补充对作物的分析的重要性，并表明铁分布标准应纳入豆类生物强化的选择策略中。
