The comparative analysis and identification of secondary metabolites between Tibet wild and cultivated pomegranates (Punica granatum L.) in China

Secondary metabolites are closely related to the nutritional quality and health functions of plants. We investigated the secondary metabolites of both wild (n=23) and cultivated (n=27) pomegranate plants (Punica granatum L.) growing in China. The total flavonoid (TF) and tannin (TT) contents from the peel and juice were determined and the secondary metabolites in the peel (ZLP) and juice (ZLZ) of 'Zela 4' were identified using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS). Analysis of variance (P<0. 05) showed that there were significant differences in the TF content of peel (TF (P)) and juice (TF (J)), and the TT content of peel (TT (P)) and juice (TT (J)) among different pomegranate accessions. Pearson correlation analysis showed that latitude and altitude might be the main environmental factors affecting TF and TT contents in pomegranates. In this study, 279 secondary metabolites were identified in the ZLP and ZLZ. In addition, we report for the first time 227 secondary metabolites in pomegranates. Using orthogonal partial least squares discriminant analysis, 90 differential metabolites were identified in ZLP and ZLZ. In addition, we screened eight specific germplasms (high-TF (P), 'Junyong 3'; low-TF (P), 'Yanzhihong'; high-TF(J), 'Zela 4'; low-TF (J), 'Yudazi', high-TT (P), 'Junyong 4'; low-TT (P), 'Anba 1'; high-TT(J), 'Yeba 1'; and low-TT (J), 'Baihuayushizi'). The results of our study provide a reference for the development and utilization of wild pomegranate resources and pomegranate breeding in China.