Evaluation of chlorogenic acid accumulation in cultivated and wild apples

Abstract Although chlorogenic acid (CGA) is a polyphenol compound with dietary benefits, the mechanism underlying its accumulation in apple fruits remains elusive. In this study, CGA content was measured in mature fruits of 379 apple accessions. A wide variation in CGA content was observed in both cultivated and wild apples. The average CGA content was significantly higher in cultivated apples than that in wild apples. Chlorogenic acid is primarily synthesized via the p-coumaroyl-CoA and quinic acid route in apple. However, no homolog encoding quinate hydroxycinnamoyl transferase (HCGQT) was identified in the apple genome, suggesting absence of CGA formation via caffeoyl glucoside and quinic acid. Additionally, transcriptional levels of two structural genes, MdPAL3 and MdHQT, were significantly correlated with CGA contents, suggesting their crucial roles in determining CGA accumulation in apple fruits. Our results will be useful for future genetic dissection and improvement of CGA accumulation in apple fruits.