To infer the phylogenetic placements of WGD events in C. chinensis, the genomic synteny within and between the genomes of A. coerulea, C. chinensis, P. somniferum, T. sinense and V. vinifera werewas identified. Within the genomes, there were only two blocks with more than 50 homologous gene pairs in C. chinensis, while there were 4, 103, 129 and 10 blocks in A. coerulea, P. somniferum, T. sinense and V. vinifera, respectively. ItThis result indicates that the C. chinensis genome had much shorter duplicated blocks than the other considered eudicot genomes (Table S1). By performing the intergenomic synteny comparisons, we identified the longest syntenic block, with 728 gene pairs, between C. chinensis chromosome 5 and A. coerulea chromosome 2 (Table S1). For the blocks with more than 10, 20 and 50 anchored gene pairs, we found that the number of syntenic genesgene pairs between C. chinensis and A. coerulea was larger than the that between C. chinensis comparing withand other genomes, indicating that the homologous region between C. chinensis and A. coerulea werewas better preserved.