Abstract: The objective of this study was to analyze the genetic background of a seedless sour orange species called‘Paoju’that is cultivated in Fujian Province using cpSSR, nSSR and genomic resequencing. We found that seven pairs of cpSSR primers could amplify 22 bands with an average of 3.14 bands per locus. The average expected heterozygosity（He）and Shannon information index（I）were 0.47 and 0.81, respectively. Thirteen pairs of nSSR primers amplified 65 bands with an average of 5 bands per locus. The average He and I were 0.66 and 1.27，respectively. A UPGMA analysis that used the data from the cpSSR and nSSR experiments demonstrated that‘Paoju’is a hybrid derived from a Citrus maxima × C. aurantium and that‘Paoju’is closely related to Daidai Sour Orange. A resequencing analysis with sweet orange as reference genome showed that the similarity rate between‘Paoju’and sour orange was more than 85%. Based on these data，we speculate that‘Paoju’may be a type of sour orange.

Key words: citrus, genetic identification, SSR, resequencing