Phylogenetic relationships among cultivars of Prunus persica based on internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA

Abstract

SummaryThe nucleotide sequences of the internal transcribed spacer (ITS) regions of nuclear rDNA were determined for 51 peach cultivars (Prunus persica L. Batch) from different eco-geographical regions of China and other countries, and compared with three related species (P. ferganensis, P. davidiana, and P. mume) and one natural inter-specific hybrid (‘Baishanbitao’). The ITS 1 region in 51 peach cultivars was 229 – 233 bp in length, the 5.8S rDNA gene was 85 bp, and the ITS 2 region was 278 – 281 bp. There were clear differences in the length of the ITS 1 region between peach cultivars originating from different eco-geographical regions. All North American and Japanese cultivars had ITS 1 regions of equal length at 229 bp and 230 bp, respectively, while Chinese cultivars showed various lengths of the ITS 1 region, ranging from 229 – 233 bp.Three groups were defined, based on phylogenetic analysis. Group I contained all the yellow peaches, except one local inter-specific hybrid Chinese yellow peach (‘Baishanbitao’), plus some Chinese ornamental and white peaches. Group II was divided into two sub-Groups. Sub-Group 1 contained only two local northwestern Chinese cultivars, and sub-Group 2 included mainly flat peaches and local northern Chinese cultivars. Also, two related species, P. davidiana and P. ferganensis, and a dwarf peach (P. persica var. densa) were clustered into sub-Group 2. Group III contained mainly Japanese white peach cultivars. P. mume was unique and not assigned to any Group. It is suggested that peaches with the genetic background of P. davidiana and P. ferganensis could be a variety of P. persica. ‘Zhanghuang 7’, ‘Wuyuexian’, and ‘Baimangpantao’ may be the oldest cultivars among those tested in this study, and ‘Baishanbitao’ is a P. davidiana × P. persica hybrid.