Abstract Organic acids strongly influence the organoleptic properties of fruit, and in citrus the major organic acid is citric acid. The pH-associated genes ( PH ) have been widely studied in various fruit and their expression has been suggested to be linked to citric acid accumulation in citrus fruit, but in planta functional evidence is lacking. A novel PH- like gene, named CrMYB73 , was isolated from ‘Ponkan’ ( Citrus reticulate Blanco) fruit, and the amino acid sequence analysis suggested that CrMYB73 was an R2R3 MYB protein. Expression of CrMYB73 was positively correlated with citric acid accumulation and its role was tested directly by overexpression in both wild type and anthocyanin-enriched transgenic Nicotiana tabacum . The results indicated that transient overexpression of CrMYB73 leads to citric acid accumulation.