Fig. 1

The uptake, transport, subcellular distribution, retranslocation, and volatilization of Se in rice. Selenate is taken up through Sultr1;1, Sultr1;2, and Sultr1;3, located in the root epidermal cell membrane, a small part of selenate enters the vacuole through Sultr4;1 located in the tonoplast, and most of it is transported to the leaves through Sultr2;1 and Sultr2;2 located in the parenchyma cell membrane of the xylem, finally enters the chloroplast through Sultr3;1, Sultr3;2, Sultr3;3, Sultr3;4, Sultr3;5, and Sultr3;6 located in the chloroplast membrane, where they are converted into SeCys and SeMet to participate in protein synthesis in a non-specific manner, and can also be further converted into DMSe and volatilized. Rice roots can take up HSeO₃⁻ and H₂SeO₃ through OsPht1;2 (OsPT2) and OsNIP2;1, respectively. After selenite enters the cytoplasm, it mainly exists in the form of HSeO₃⁻ and SeO₃²⁻; part of the selenite enters the vacuole through OsSPX-MFS1/3 and OsVPE1/OsVPE2 located in the tonoplast. Selenite mainly exists in the form of H₂SeO₃ and HSeO₃⁻ in the vacuole; most of it is transported to the plastid by OsPHT4;1-OsPHT4;4 and OsPHT2;1 and converted into SeCys and SeMet, and then participate in protein synthesis non-specifically, and can also be further converted into DMSe and volatilizes. Part of SeMet is transported to shoots through NRT1.1B and participates in protein synthesis. In senescent leaves, protein is encapsulated in autophagic vesicles and transported to vacuoles, degraded into SeMet by proteases, and transported to rice grains through OsAAP1, OsAAP3, and OsNRT1.1B. Sulfate transporters,  ; OsNIP2;1,  ; Phosphate transporters,  ; NRT1.1B,  ; Amino acid transporters,  ; Anion channels,   Solid lines correspond to identified transporters and dashed lines correspond to potential transporters