OsMTP11, a trans-Golgi network localized transporter, is involved in manganese tolerance in rice

Metal tolerance proteins (MTPs) belong to the cation diffusion facilitator family (CDF) and have been implicated in metal transport and homeostasis in different plant species. Here we report on the rice gene OsMTP11 that encodes a putative CDF transporter that is homologous to members of the Mn-CDF cluster. The expression of OsMTP11 was found to enhance Mn tolerance in the Mn-sensitive yeast mutant pmr1. Knockdown of OsMTP11 resulted in growth inhibition in the presence of high concentrations of Mn, and also led to increased accumulation of Mn in the shoots and roots. The overexpression of OsMTP11 was found to enhance Mn tolerance in rice, and under supplementation with a toxic level of Mn, decreased Mn concentration was observed in the shoots and roots. Subcellular localization in rice protoplasts and tobacco epidermal cells revealed that OsMTP11 localizes to the trans-Golgi network (TGN), and a significant relocalization to the plasma membrane can be triggered by high extracellular Mn in tobacco epidermal cells. These findings suggest that OsMTP11 is a TGN-localized Mn transporter that is required for Mn homeostasis and contributes towards Mn tolerance in rice.