Manganese homeostasis and detoxification in plants: the role of Cation Diffusion Facilitators

锰（Mn）是植物必需的元素，但过量的锰可引起毒性症状。因此，锰营养失衡会严重限制作物生长和生产力。锰利用和解毒的效率取决于金属的摄取、（再）转运和细胞内分布。由于这些过程涉及锰跨膜的运动，锰转运蛋白是锰稳态的主要决定因素。然而，由于锰转运蛋白的身份在很大程度上是未知的，因此对植物中锰稳态的控制知之甚少。阳离子扩散促进剂（CDF）蛋白家族编码各种过渡金属的转运蛋白，包括锰。该家族包括多个尚未被鉴定的植物中假定的mn转运成员。初步实验表明，这些基因参与了与锰有关的过程。为了揭示这些基因在锰稳态和解毒中的作用，我们将研究(1)它们在酵母突变体中表达的选择性和转运活性，(2)它们在模式植物拟南芥中的表达模式，(3)它们的亚细胞定位，(4)它们在锰依赖过程中的功能，以及(5)它们对锰转运和积累的影响。该项目对锰迁移的进一步了解可以用于设计更好地适应锰可用性普遍条件的作物。

Manganese (Mn) is an essential element for plants, but excessive availability of Mn can cause toxicity symptoms. Imbalances in Mn nutrition can therefore severely limit crop growth and productivity. Efficiency of Mn use and detoxification depend on uptake, (re-)translocation and intracellular distribution of the metal. As these processes involve the movement of Mn across membranes, Mn transporters are a major determinant for Mn homeostasis. However, the control of Mn homeostasis in plants is poorly understood because the identity of the Mn transport proteins is largely unknown. The Cation Diffusion Facilitator (CDF) protein family encodes transport proteins for various transition metals, including Mn. The family includes multiple putatively Mn-transporting members in plants which have not yet been characterized. Initial experiments showed that these genes are involved in Mn-related processes. To reveal the roles of those genes in Mn homeostasis and detoxification, we will study (1) their selectivites and transport activities by expressing the genes in yeast mutants, (2) their expression patterns in the model plant Arabidopsis, (3) their subcellular localization, (4) their function in Mn-dependent processes, and (5) their effect on Mn translocation and accumulation. The improved understanding of Mn transport resulting from this project can be utilized to design crops better adapted to the prevalent conditions of Mn availability.