Evaluation of Phenolic Composition and Content of Pear Varieties in Leaves from China

In this study, we assessed the main phenolic compounds in leaves of 90 pear germplasm resources, including 26accessions of P.bretschneideri, 24accessions of P.pyrifolia, 40accessions of P.ussuriensis to determine the diversity of phenolic compounds among these pear species and to analyse the relationships among the contents and profiles of phenolic compounds. The average contents of total phenolic compounds of different pear species in leaves were in the range of 17.02-21.11mg/g. Arbutin was detected as major phenolic compound in the leaves which contributed almost 32.3% of the total amount of phenol compounds in the assayed samples, and about 86.7% of the varieties had highest arbutin content than other individual phenolic compounds. Principal component analysis (PCA) showed that P.bretschneideri and P.pyrifolia accessions were not noticeably discriminated with each other based on their phenolic content and profile, while P.ussuriensis accessions were markedly distinguished mostly according to the second principal component variation, and also wild P.ussuriensis and cultivated P.ussuriensis accessions showed obvious discriminating between each other. The specific organization of the pear species based on the accumulation of secondary metabolites showed ahigh consistency with the phylogenetic organization known. Partial least squares discriminant analysis (PLS-DA) showed that the phenolic composition in leaves resolved variation in difference pear species from China, and the variation was mainly attributed to four compounds. This study provides new insights into phenolic diversity of pear germplasm resources.