## 2 Results
### Cloning and Bioinformatics Analysis of PsTPS1  
The complete ORF of _PsTPS1_ was 1662 bp (Figure 4A) and encoded 553 amino acids (Figure S2). The theoretical relative molecular weight of the PsTPS1 protein was 63.63 kD, and the theoretical pI was 5.25. The total number of negatively charged residues (Asp + Glu) was 73, and the total number of positively charged residues (Arg + Lys) was 53. The secondary structure predicted that PsTPS1 contained 378 \(\alpha\)-helix (68.35%), 126 random coil (22.78%), 31 extended strands (5.61%), and 18 \(\beta\)-turns (3.25%) (Figure 4B). The GMEQ value for tertiary structure modeling was 0.92, and the results suggested that PsTPS1 protein had a high similarity of 72.54% with the TPS01 model of _Liquidambar formosa_ (Figure 4C). TMHMM and signal peptide analyses also showed PsTPS1 had no signal peptide and transmembrane structural (Figure 4D,E). And PsTPS1 protein exhibited a hydrophilic and unstable nature with a GRAVY value of \(-\)0.237, aliphatic index of 92.06, and instability index of 46.39 (Figure 4F). The conserved domains analysis revealed that PsTPS1 contained a Terpene_cyclase_plant_C1 (Isopernoid_Biosyn_C1 surperfamily) domain with terpene synthase activity (Figure 4G).  
Figure 1: Photos of cultivar _P. suffruticosa_ ‘Oukan’. (**A**) Four different flower developmental stages. Stage 1, bud brusting stage; Stage 2, initial flowering stage; Stage 3, full blooming stage; Stage 4, flower withering stage. (**B**) Different organs and tissues in Stage 3.  
Figure 2: The electrophoresis map of the _PsHMGR1_ gene and PsHMGR1 protein characterization. (**A**) Electrophoresis map of _PsHMGR1_ gene. M, marker. (**B**) Secondary structure prediction, (**C**) 3D model building, (**D**) transmembrane helices prediction, (**E**) hydrophobicity or hydrophilicity analysis, (**F**) signal peptide analysis, and (**G**) conserved domains analysis of PsHMGR1 protein.  
Figure 3: Phylogenetic tree and multiple sequence alignment of HMGR proteins. (**A**) Phylogenetic tree of PsHMGR1 and HMGR protein from other 37 plant species, using the IQ-TREE of TBtools V2.136 software. Bootstrap values are shown as a percentage of 5000 replicates. PsHMGR1 is marked with a green dot. Clades of various species are highlighted with different color lines. Dt, _Dillenia turbinata_; Tw, _Tritpergium wilfordii_; Rc, _Ricinus communis_; Pt, _Populus trichocarpa_; Nn, _Nelumbo nucifera_; Pe, _Populus euphraticia_; Mi, _Mangifera indica_; Pa, _Populus alba_; Pv, _Pistacia vera_; JC, _Jatropha curcas_; Ca, _Chlorodybus atnoplyticus_; Mv, _Mesostigma viride_; Pp, _Phycointella patens_; Mp, _Marchantia polymorpha_; As, _Alsophila simulos_; Cr, _Centaqteris richardi_; Ac, _Adiantum capillus_; Pta, _Pinus tabuliformis_; Gb, _Ginkgolibou_; Atr, _Amborella trichopoda_; Os, _Oryza sativa_; Zm, _Za musy_; Oe, _Olea europaea_; Vv, _Vitis vinifera_; At, _Arabidopsis thaliana_; Hs, _Homo sapiens_; Rn, _Rattus norgegicus_; Da, _Drosophila albolomicus_; Sc, _Saccharomyces cerevisiae_; Gl, _Ganderna lucidum_; Lh, _Lachnellula hyalina_; Zg, _Zobellia galacantivorans_; Sm, _Streplomyces malayisensis_; Bl, _Brevol bacterium linens_. (**B**) Alignment and analysis of PsHMGR1 with HMGR protein sequences of _D. turbinata, P. trichocarpa_, and _T. wilfordii_. Motif I, E(M/L)(P/J)GY(V/I)Q(I/L)P; motif II, TTEGCLVA; motif III, DAMGMNM; motif IV, GTVGGGGT. Accession information of HMGR proteins of other 37 plant species is detailed in Supplemental Table S1.