Parental chromosome differentiation in citrangequat [Fortunella sp. × (Citrus sinensis × Poncirus trifoliata)] using CMA banding patterns

The efficiency of chromomycin A₃ (CMA) staining was examined for parental chromosome differentiation in citrange Citrus sinensis (L.) Osbeck × Poncirus trifoliata (L.) Raf.] and citrangequat (Fortunella sp. × citrange). All of the accessions analyzed had the same chromosome number of 2n = 18. CMA staining revealed six characteristic banding patterns on the basis of the number and position of CMA positive bands (CMA⁺) as follows; A: two terminal and one proximal band, B: one terminal and one proximal band, C: two terminal bands, D: one terminal band, E: no band, and F: one proximal band. Chromosome CMA banding patterns of the accessions were 1A + 1B + 2C + 13D + 1F in Fortunella margarita, 2B + 2C + 7D + 7E in ‘Fukuhara’ orange, 2B + 10D + 6E in Poncirus trifoliata, 1B + 1C + 10D + 6E in citrange and 1A + 1C + 11D + 4E + 1F in citrangequat. The results of this study confirmed the intergeneric and tri-generic hybridity of citrange and citrangequat, respectively.