Abstract:

28 accessions of trifoliate orange (Poncirus trifoliata Raf.), hybrids and seven accessions of its relatives, were analyzed for genetic diversity and phylogenetic relationship using nuclear and chloroplast SSR markers. Average PIC (Polymorphism Information Content) value of 0.51 and average expected heterozygosity of 0.52 were given according to nuclear SSR results. 22 common trifoliate orange accessions could be divided into four groups with a genetic distance of 0.16. It indicates a rich genetic diversity of China trifoliate orange germplasm. cpSSR revealed no difference among common trifoliate orange accessions which indicates a relatively conservative chloroplast genome. Four cpSSR loci were found different between Fumin（P. polyandra S. Q. Ding et al.）and common trifoliate orange. Fumin trifoliate orange is genetically distant from common trifoliate orange, from its hybrids as well as relatives. It therefore could be regarded as a true species. The combined application of nuclear and chloroplast SSR could serve a more accurate way to identify trifoliate orange hybrids.

Key words: Poncirus trifoliata, SSR, cpSSR, genetic diversity, phylogenetic relationship