Abstract:

In this study，we sampled a total of 95 samples，including 35 landraces and 35 wild individuals of Chinese cherry from 6 populations across 35 counties of 8 provinces in China，18 cultivars of European sweet cherry from 10 countries in the world，as well as 7 semi-wild Nanking cherry resources from 7 counties of 5 provinces in China. Based on internal transcribed spacer（ITS）sequences，we tried to study the genetic diversity within species and interspecific relationship among them. The final ITS dataset contained 712 aligned nucleotides，with 58.1% of G + C content，of which 71（9.97%）were variable sites. The ITS sequences defined 37 haplotypes. The haplotype diversity（Hd）and nucleic acid diversity（π）of C. pseudocerasus，C. avium，and C. tomentosa were（0.840，0.00466），（0.928，0.00396）and（0.905，0.00564），respectively. Within C. pseudocerasus，the genetic diversity of germplasm（Hd = 0.726，π = 0.00224）was significantly lower than that of wild resource（Hd = 0.914，π = 0.00681）. Interspecific genetic relationship analysis showed close relationship（0.019）between Chinese cherry and sweet cherry，while they revealed further relationship with Nanking cherry. Both Neighbor-Joining reconstruction and haplotype network showed three distinct branches with obvious genetic differentiation among the three species. In addition，there were significant differences in the secondary structure of the ITS1 and ITS2 regions and t-detection of the minimum free energy. Based on above results，there were high genetic diversity and obvious genetic differentiation among three cherry cultivated species. Close relationship was detected between Chinese cherry and European sweet cherry，while far distance between Nanking cherry with them.

Key words: Cerasus pseudocerasus, C. avium, C. tomentosa, ITS sequence, haplotype, genetic diversity, interspecific relationship