The Tonoplast-Localized Transporter OsNRAMP2 is involved in Fe Homeostasis and affects Seed Germination in rice

• Published in: Journal of experimental botany 2021-04
• Main Authors: Li, Yun, Li, Jingjun, Yu, Yihong, Dai, Xia, Gong, Changyi, Gu, Dongfang, Xu, Ending, Liu, Yiheng, Zou, Yu, Zhang, Peijiang, Chen, Xi, Zhang, Wei
• Format: Article
• Language: English
• ISSN: 1460-2431

Vacuolar storage of iron (Fe) is important for Fe homeostasis in plants. When sufficient, the excess Fe could be stored in vacuoles for remobilization in case of Fe deficiency. Although the mechanism of Fe remobilization from vacuoles is critical for crop development under low Fe stress, the transporters that mediate vacuolar Fe translocation into the cytosol in rice remains unknown. Here, we showed that under higher Fe2+ concentrations, the Δccc1 yeast mutant transformed with rice natural resistance-associated macrophage protein 2 (OsNRAMP2) became more sensitive to Fe toxicity. In rice protoplasts and transgenic plants expressing Pro35S: OsNRAMP2-GFP, OsNRAMP2 was localized to tonoplast. Vacuolar Fe contents in osnramp2 knockdown lines were higher than in the wild-type, while the growth of osnramp2 knockdown plants was significantly influenced by Fe deficiency. Furthermore, the germination of osnramp2 knockdown plants was arrested. Inversely, the vacuolar Fe contents of Pro35S: OsNRAMP2-GFP lines were significantly lower than in the wild-type, and overexpression of OsNRAMP2 increased shoot biomass under Fe deficiency. Taken together, we propose that OsNRAMP2 transports Fe from the vacuole to the cytosol and plays a pivotal role in seed germination.