School of Agriculture, Policy and Development, University of Reading, Earley Gate, Reading, RG6 6AR, UK.
Department of Nutritional Sciences, University of Wisconsin-Madison, Madison, WI, 53706, USA.
Sci Rep. 2018 Sep 26;8(1):14412. doi: 10.1038/s41598-018-32819-y.
The presence of the toxic metal cadmium (Cd) in certain foodstuffs is recognised as a global problem, and there is increasing legislative pressure to reduce the content of Cd in food. The present study was conducted on cacao (Theobroma cacao), the source of chocolate, and one of the crops known to accumulate Cd in certain conditions. There are a range of possible genetic and agronomic methods being tested as a route to such reduction. As part of a gene-based approach, we focused on the Natural Resistance-Associated Macrophage Proteins (NRAMPS), a family of proton/metal transporter proteins that are evolutionarily conserved across all species from bacteria to humans. The plant NRAMP gene family are of particular importance as they are responsible for uptake of the nutritionally vital divalent cations Fe, Mn, Zn, as well as Cd. We identified the five NRAMP genes in cacao, sequenced these genes and studied their expression in various organs. We then confirmed the expression patterns in response to variation in nutrient cation availability and addition of Cd. Functional analysis by expression in yeast provided evidence that NRAMP5 encoded a protein capable of Cd transport, and suggested this gene as a target for genetic selection/modification.
某些食品中存在有毒金属镉（Cd），这已被认为是一个全球性问题，因此越来越多的立法压力要求降低食品中的 Cd 含量。本研究以可可（Theobroma cacao）为对象，可可为巧克力的原料，在某些条件下，可可被认为是一种会积累 Cd 的农作物。目前正在测试一系列可能的遗传和农业方法，以实现这一目标。作为基于基因的方法的一部分，我们专注于天然抗性相关巨噬细胞蛋白（Natural Resistance-Associated Macrophage Proteins，NRAMPS），这是一组质子/金属转运蛋白，在从细菌到人等所有物种中都具有进化保守性。植物 NRAMP 基因家族尤为重要，因为它们负责摄取营养必需的二价阳离子 Fe、Mn、Zn 以及 Cd。我们在可可中鉴定了五个 NRAMP 基因，对这些基因进行了测序，并研究了它们在各种器官中的表达情况。然后，我们根据营养阳离子可用性的变化和 Cd 的添加来确认表达模式。通过在酵母中的表达进行功能分析，提供了证据表明 NRAMP5 编码的蛋白能够转运 Cd，并将该基因作为遗传选择/修饰的靶标。
