*4.3. Chromosomal Location and Tandem Duplication Analysis*

The information on location for each *RcSWEET* gene was obtained from the GFF genome annotation of *R. chinensis* 'Old Blush'. The chromosomal localization of the *Rc-SWEET* genes was mapped using MapChart (2.3.2) software [69]. The MCscanX software was used to search for tandem and duplicated genes. The Ka and Ks values for duplicated gene pairs (Table S4) were calculated based on the coding sequence alignments using the Ka/Ks calculator in TBtools [46].

#### *4.4. Cis-Acting Element Analysis*

The upstream sequences (2000 bp) of the 25 *RcSWEET* coding sequences were retrieved and then submitted to PlantCARE (http://bioinformatics.psb.ugent.be/webtools/ plantcare/html/, accessed on 18 December 2022) to identify cis-acting elements [70]. The prediction results of cis-acting elements were illustrated by GSDS.
