Genetic diversity and genetic relationship of Vietnamese Citrus varieties using internal transcribed spacer region (ITS)

Vietnam is considered to be the center of origin of many Citrus species. Regional structures of territory, climatic and soil conditions are suitable and favorable for Citrus production as well as rich in germplasm resources. In this study, 15 Citrus samples were collected in different areas and identified by ITS sequencing. The results showed that the nucleotide sequences and the coverage of the samples were ranged from 95.60%to 99.86% and were 97.0% to 99.0%, respectively, as compared with the published reference samples. Specifically, the C9 sample (Cam Duong Ha Tinh) had a similar level with the reference samples of JN681155.1 Citrus maxima (99.72%), which was higher than the homologous sample of JN681165.1 Citrus sinensis by 98.46%. The C10 sample (Cam Sanh Bo Ha) was similar to the reference sample MH721728.1 Citrus reticulata (99.72%), higher than the reference JN681150.1 Citrus sinensis up to 99.45%. Based on the ITS genome sequences, 6/15 Citrus samples were accurately identified. The results also indicate that Vietnamese native Citrus varieties are diversified in the genus Citrus species. Our findings have provided useful information for the accurate identification of some native Citrus germplasms in this country.