*4.1. Identification of the SWEET Family Genes in R. chinensis*

The genome sequence and annotation of *R. chinensis* 'Old Blush' were downloaded from the NCBI genome database (https://www.ncbi.nlm.nih.gov/genome/?term=rosa+ chinensis, accessed on 18 December 2022) [48]. The Hidden Markov Model (HMM) profiles of the SWEET domain (PF03083) were downloaded from the Pfam database (http://pfam. xfam.org/, accessed on 18 December 2022) and used to search the SWEET proteins of *R. chinensis* with HMMER (3.3.2) software (e-value < 0.01) [64]. In addition, the protein sequences of 17 AtSWEETs [1] were downloaded from TAIR (http://www.arabidopsis.org/, accessed on 18 December 2022) and used as queries to search the *R. chinensis* proteome by using BLASTP with an e-value threshold of 1 × <sup>10</sup><sup>−</sup>5. Then the results of the two methods are intersected to obtain the candidate sequences, whose conserved domains were further

identified by the Pfam database (https://pfam.xfam.org/search#tabview=tab1, accessed on 18 December 2022) and the Conserved Domain Database (http://www.ncbi.nlm.nih. gov/Structure/cdd/wrpsb.cgi/, accessed on 18 December 2022). Finally, the ProtParam tool (http://web.expasy.org/prot-param, accessed on 18 December 2022) was used to analyze the sequence length, molecular weight, and theoretical isoelectric point values of each RcSWEET protein. The transmembrane helix of RcSWEET proteins was predicted by the TMHMM Server version 2.0 (http://www.cbs.dtu.dk/services/TMHMM/, accessed on 18 December 2022) [65].

## *4.2. Gene Structure, Motif, and Phylogenetic Analysis*

Based on the genomic sequence and coding sequence, the gene structure of *RcSWEET* genes was predicted by the Gene Structure Display Server (GSDS; http://gsds.gao-lab.org/, accessed on 18 December 2022) [66]. The conserved motifs in full-length SWEET proteins were identified by MEME (https://meme-suite.org/meme/tools/meme, accessed on 18 December 2022) [67]. Multiple sequence alignments were carried out considering the full-length SWEET protein sequences from *A. thaliana, O. sativa*, and *R. chinensis* (Table S3). Subsequently, an unrooted neighbor-joining (NJ) tree was constructed by MEGA 7.0 with 1000 bootstrap replications [68].
