GENETIC CLUE TO THE ORIGIN OF CULTIVATED ASIAN PEARS INFERRED FROM CPDNA HAPLOTYPES

Chinese white pears (CWP), Chinese sand pears (CSP), Ussurian pears (UP) and Japanese pears (JP) are four major cultivated pear groups native to Asia. Their origin and genetic relationships remain controversial. In this study, 475 pear cultivars and local cultivars from Asia were genotyped using cpDNA accD-psaI to elucidate the origin and genetic relationship of cultivated Asian pear groups. As a result, seven haplotypes were identified (Hap1-Hap7). Hap1, Hap2 and Hap3 were found in the most accessions, referred to as dominant haplotypes. The other four haplotypes were mostly limited to accessions from south China. The Neighbor-Net network of the total 7 haplotypes showed that the Hap5 was the ancestral haplotype, and Hap1 was the most evolved one. The proportion of Hap1 increased in all accessions from west to east China, while that of Hap2 decreased. CSP covered all of the seven haplotypes and displayed the highest level of genetic diversity, while CWP only had four haplotypes with the highest proportion of Hap1. Therefore, CWP might represent the most evolved lineages of CSP. JP only had three dominant haplotypes (Hap1, Hap2, and Hap3), the proportion of halplotypes was much similar to CSP cultivars from Zhejiang (ZJ) and Fujian (FJ) Province. In addition, UP had four haplotypes (Hap1, Hap2, Hap3 and Hap5), of which Hap3 was the dominant haplotype.