## 2 Results
### Identification and Quantification of Volatile Compounds  
The HS-SPME-GC-MS analysis identified a wide range of VOCs from the 28 melon breeding lines (Table 3). The 113 VOCs detected in the 28 melon lines included 27 aldehydes, 15 esters, 35 alcohols, 14 ketones, 10 hydrocarbons, 4 acids, and 5 sulfur-containing VOCs (Table 3). The other 3 volatiles identified were benzeneacetonitrile, 2-pentylfuran, and methoxyphenyl-oxime. A typical chromatograph representing the melon VOCs in BL-20 is shown in Figure 1.  
The highest total VOC content was found in BL-30 (13,973.07 ug/kg FW), whereas the lowest was found in BL-22 (3947.13 ug/kg FW); BL-20 had the most different VOCs (77) and BL-22 had the fewest different VOCs (42) (Table S1, Figure 2). \begin{table}
\begin{tabular}{c c c c} \hline
**Name** & **L\({}^{*}\)** & **b\({}^{*}\)** & **a\({}^{*}\)** \\ \hline BL-1 & \(73.90\pm 0.76\)a & \(46.58\pm 1.94\)abc & \(21.02\pm 0.89\)a \\ \hline BL-4 & \(59.94\pm 3.59\)abc & \(41.02\pm 2.28\)abcd & \(19.19\pm 1.21\)ab \\ \hline BL-6 & \(73.11\pm 11.74\)ab & \(39.21\pm 3.98\)bcd & \(20.56\pm 0.704\)c \\ \hline BL-7 & \(59.46\pm 8.00\)abc & \(39.29\pm 4.16\)bcd & \(17.66\pm 1.84\)ab \\ \hline BL-8 & \(73.57\pm 3.13\)a & \(45.07\pm 4.04\)abc & \(16.37\pm 1.68\)abc \\ \hline BL-9 & \(54.60\pm 5.37\)bc & \(40.70\pm 3.32\)abcd & \(23.30\pm 1.49\)a \\ \hline BL-11 & \(62.48\pm 7.54\)abc & \(40.73\pm 1.69\)abcd & \(17.75\pm 1.14\)ab \\ \hline BL-12 & \(62.76\pm 6.68\)abc & \(42.58\pm 2.73\)abcd & \(20.65\pm 1.45\)a \\ \hline BL-14 & \(70.56\pm 1.26\)abc & \(47.70\pm 0.79\)ab & \(20.86\pm 0.32\)a \\ \hline BL-15 & \(57.58\pm 2.69\)abc & \(41.26\pm 2.05\)abcd & \(20.53\pm 1.02\)a \\ \hline BL-17 & \(67.18\pm 6.27\)abc & \(45.54\pm 2.45\)abc & \(22.43\pm 1.46\)a \\ \hline BL-18 & \(63.03\pm 7.81\)abc & \(42.89\pm 4.73\)abcd & \(21.35\pm 1.93\)a \\ \hline BL-19 & \(67.26\pm 0.36\)abc & \(49.06\pm 1.10\)a & \(27.09\pm 1.10\)a \\ \hline BL-20 & \(72.96\pm 2.81\)ab & \(46.13\pm 2.89\)abc & \(20.48\pm 1.76\)a \\ \hline BL-21 & \(66.65\pm 8.37\)abc & \(44.88\pm 4.18\)abc & \(20.61\pm 1.75\)a \\ \hline BL-22 & \(68.14\pm 10.63\)abc & \(44.59\pm 6.42\)abc & \(18.71\pm 1.77\)ab \\ \hline BL-24 & \(66.06\pm 7.51\)abc & \(46.11\pm 3.40\)abc & \(22.01\pm 0.70\)a \\ \hline BL-25 & \(53.43\pm 8.03\)c & \(37.59\pm 4.61\)cd & \(20.87\pm 1.69\)a \\ \hline BL-26 & \(56.46\pm 2.11\)abc & \(40.37\pm 1.09\)abcd & \(17.04\pm 0.87\)abc \\ \hline BL-28 & \(64.05\pm 8.70\)abc & \(41.71\pm 5.70\)abcd & \(18.31\pm 1.53\)ab \\ \hline BL-30 & \(62.55\pm 10.87\)abc & \(41.22\pm 4.93\)abcd & \(20.12\pm 1.48\)ab \\ \hline BL-33 & \(68.97\pm 11.56\)abc & \(34.83\pm 5.32\)d & \(15.39\pm 1.50\)bc \\ \hline BL-34 & \(64.51\pm 8.02\)abc & \(40.48\pm 3.35\)abcd & \(17.07\pm 2.22\)abc \\ \hline BL-35 & \(56.97\pm 2.54\)abc & \(43.30\pm 2.49\)abcd & \(21.71\pm 1.99\)a \\ \hline BL-36 & \(60.63\pm 1.96\)abc & \(42.41\pm 2.70\)abcd & \(20.33\pm 2.41\)a \\ \hline BL-40 & \(55.16\pm 2.29\)abc & \(41.67\pm 2.64\)abcd & \(19.45\pm 0.75\)ab \\ \hline BL-43 & \(66.50\pm 3.45\)abc & \(44.09\pm 0.26\)abcd & \(20.24\pm 0.33\)a \\ \hline BL-100 (10) & \(72.94\pm 0.56\)ab & \(48.44\pm 1.11\)ab & \(18.25\pm 1.38\)ab \\ \hline \end{tabular}
\end{table} 
Table 1: Color attributes L\({}^{*}\) (lightness), b\({}^{*}\) (blue to yellow), a\({}^{*}\) (green to red) in melon breeding lines. Means with the same letter indicate no significant difference.