## 2 Results  
### Volatile Aroma Characteristics of Pepper Fruit from Different Samples  
The specific sample phenotype information is shown in Figure 1 and Table S1, the total ion chromatograms for the GC-MS detection are shown in Figure S1, and the QC sample quality test is shown in Figure S2. A total of 149 VACs were identified in 36 samples (four varieties \(\times\) three developmental stages \(\times\) three biological replicates) and were composed of 53 esters (35.57% of the total), 27 aldehydes (18.12%), 10 alcohols, 20 hydrocarbons (13.42%), 20 terpenoids (13.42%), and 19 other VACs (Table 1). As the dominant volatiles, esters mainly include Z17 (trans-2-hexenyl isovalerate), Z11 (methyl salicate), Z7 (n-amyl isovalerate), Z29 (6-methylhept-4-en-1-yl 3-methyl-butanoate), Z12 (4-methylpentyl 2-methylbutanoate), Z28 (6-Methyl-4-heptenyl 2-methylbutanoate), Z39 (4-methylpentyl 8-methylmonanoate) components, followed by aldehydes such as Q3 (Hexanal), Q4 (e-2-hexenal), Q16 (9-undecenal, 2,10-dimethyl-l), Q21 (pentadecanal), etc. The third largest number are terpen and hydrocarbons, the former mainly including T3 (Z-\(\beta\)-Farnesene), T4 (himach-ala-2,4-diene), T1 (\(\alpha\)-Cubenene), T20 (\(\alpha\)-Ionone), the latter comprising TH15 (hexade-cane), TH4 (2-methyl-hexadecane), TH12 (tetradcane), etc. In this experiment, only three ketones and four phenolic components were detected. Figure 1: Phenotype plots of pepper fruits from different samples. CTJ: Chaotian pepper; HDL1: Hainan Huangdenglong pepper; GJ: ghost pepper; HDL2: hybrid Huangdenglong pepper; “a”: green stage; “b”: breaking stage; “c”: maturation stage. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline
**RT** & **C48** & **Stage** & \multicolumn{4}{c}{**Cons-Stage**} & \multicolumn{4}{c}{**Baseline Stage**} & \multicolumn{4}{c}{**Model-Stage**} \\ \hline
**RT** & **C48** & **C48** & **C  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c} \hline \hline  & \multicolumn{2}{c}{**Step**} & \multicolumn{2}{c}{**Connect Strip**} & \multicolumn{2}{c}{**Randomized Step**} & \multicolumn{2}{c}{**Randomized Step**} \\ \hline
**M** & **C** & **C** & **A** & **A** & **A** & **A** & **A** & **C** & **G** & **B** & **B**  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c} \hline
**ST** & **Cats** & \multicolumn{2}{c}{**Number**} & \multicolumn{2}{c}{**Comms Step**} & \multicolumn{2}{c}{**Readings Step**} & \multicolumn{2}{c}{**Modernism Step**} \\ \cline{3-14}  & **A** & **A** & **A** & **A** & **A** & **A** & **A** & **A** & **C** & **G** & **A  
We found that the types of volatile compounds detected in different samples were basically the same, while the total relative content of volatiles showed obvious recognizable differences (Figure 2a and Table 1). With the development of fruits, the relative content of total volatiles in GJ and HDL1 gradually increased from 663.67 ug/kg and 811.76 ug/kg to 931.69 ug/kg and 1210.62 ug/kg, respectively. CTJ showed a trend of increasing first and then decreasing, with a maximum value of 761.66 ug/kg, while HDL2 showed a trend of decreasing from 1082.97 ug/kg at the green stage to 796.88 ug/kg at the mature stage. In addition, the concentration of total VACs compounds between different varieties at the same stage showed noticeable differences, and the concentration of total VACs in HDL2 (1082.97 ug/kg) was significantly higher than that of other varieties at the green stage, while HDL1 was significantly higher than other varieties at the breaking stage (1070.67 ug/kg) and mature stage (1210.62 ug/kg). The relative content of VACs (esters, aldehydes, alcohols, terpenoids, etc.) from different samples exhibited a dynamic change in different groups (Figure 2b and Table S2). In the four varieties, the content ratio of volatile esters in HDL1 and HDL2 during the whole stage reached 50-60%, which was much higher than that of other groups.