Changes in sugar and organic acid concentrations during fruit maturation in peaches, P. davidiana and hybrids as analyzed by principal component analysis

Changes during fruit maturation in sugar and acid concentrations were determined and compared for cultivated peaches (cv. Summergrand and Zéphir), P. davidiana and their unselected BC2 genotypes. Cultivated peaches, P. davidiana as well as BC2 genotypes followed similar changes in sucrose, citric acid, quinic acid and shikimic acid during fruit maturation. Sucrose increased until maturity; citric acid increased then fell; quinic acid and shikimic acid declined at maturity. There were very large differences in changes of glucose, fructose, sorbitol and malic acid during fruit maturation among the parents and BC2 genotypes studied. Principal component analysis (PCA) was used to describe temporal changes for complex traits and analyze the relationship between parents and BC2 genotypes. In young immature fruits malic acid, quinic acid and shikimic acid concentrations were high then declined. Citric acid concentration peaked at intermediate maturities while mature fruits were characterized by increased sugar concentrations, especially sucrose. According to main PCA score planes, no BC2 genotype was identical to 'Summergrand', 'Zéphyr' or P. davidiana parents. BC2 genotypes were much closer to the cultivated peaches than to P. davidiana.