*2.7. Subcellular Localization of Three RbSWEET Genes*

Based on the expression patterns of the *SWEET* genes in both species, three *RbSWEET* genes were selected for subcellular localization. *RbSWEET1*, *RbSWEET2a*, and *RbSWEET10c* were transiently overexpressed in tobacco leaf epidermal cells. As shown in Figure 8, *RbSWEET1* and *RbSWEET10c* were found to be localized to the plasma membrane, and *RbSWEET2a* was found to be localized to the tonoplast, whereas the control (GFP alone) was observed clearly in the plasma membrane, cytoplasm, and nucleus.

**Figure 7.** Expression levels of DEGs or highly expressed *SWEET* genes in *R. chinensis* 'Old Blush' and *R. beggeriana* via qRT-PCR. Error bars indicate standard deviation, and asterisks indicate significant differences between the control (0 h) and 4 ◦C treatment for 1 h, 6 h, 24 h, \* *p* < 0.05, \*\* *p* < 0.01, \*\*\* *p* < 0.001, and \*\*\*\* *p*< 0.0001.

**Figure 8.** Subcellular localization of RbSWEET-GFP fusion proteins in tobacco leaves.
