Variation of phytochemical composition of Lycium chinense leaves as an endemic high-value healthy resource

Lycium chinense, belonging to the Solanaceae family and Lycium genus, is an important healthy resource with abundant nutritional and functional components, which leaves has been developed as popular medicinal vegetable and healthy herbal tea. However, little systemic evaluation has been taken on the germplasm quality of L. chinense leaves in China. In this study, the contents variation of the main active compounds (polysaccharides, flavonoids, rutin and chlorogenic acid) and nutrients (crude protein, amino acids, mineral elements and reducing sugar) of different L. chinense populations among different regions and different years and seasons were investigated by common-garden experiment. The results indicated a significant difference in the contents of functional components among the different populations. The SS (Shishou) population has the highest average contents and stability of total flavonoid (64.25 mg RE/g dw), rutin (16.95 mg/g dw), and chlorogenic acid (7.19 mg/g dw), followed by the LT (Luotian) population. The steadily highest contents of crude protein (6.25 g/100 g fw) and total amino acids (44.92 g/100 g fw) contents were detected in the XS (Xinshan) population. Little changes in the components contents of L. chinense leaves were showed in different growth stages, which indicated that L. chinense leaves could have the longer harvesting period. Moreover, there was a significant correlation between the functional components and the geographic location. For example, we found flavonoids and polysaccharides of L. chinense showed the highest content in Central and South China, respectively. In addition, the mean annual temperature (MAT) was the environmental factor with the highest degree of correlation with most of the functional components. This study provides important information on the exploration of quality resources and further breeding of L. chinense germplasm resources.