Microsatellite polymorphic loci reveal genetic structure of cultivated pears in East Asia
The origin and genetic relationships between Chinese white pears (CWP), Chinese sand pears (CSP), Ussurian pears (UP), and Japanese pears (JP) remain controversial. In this study, an unprecedented large number of 423 pear cultivars and local landraces from East Asia were collected and genotyped with thirty-eight SSR loci, which were spreading across 17 chromosomes in the pear genome, to elucidate the genetic structure and genetic relationships of these cultivated pear groups. As a result, these 38 loci showed high polymorphism, a total of 850 different alleles were detected, with an average of 22.4 alleles locus-1. Shannon's Information index (I) of each locus ranged from 0.900 (KA4b) to 3.757 (CH01F02). The expected heterozygosity (He) at different loci ranged from 0.380 (KA14) to 0.913 (CH01F02) with an average of 0.787. All cultivated pears were further divided into 14 geographical populations according to their geographic origin. The He of different pear populations ranged from 0.725 (JP) to 0.829 (UP), and allelic richness of them ranged from 3.352(JP) to 5.489 (UP). By use of Bayesian statistical inference, cultivars belonging to the different cultivated pear groups were classified into four clusters. Further AMOVA analysis displayed that different kinds of groupings were not well differentiated from each other and no real genetic differentiation were detected between CSP and CWP. The results of neighbor-joining clustering demonstrated that JP was most similar to cultivars from Zhejiang province (ZJ), which is in accordance with our previous results.
Yue, X., Teng, Y., Zheng, X., Liu, G. and Hu, C. 2017. Microsatellite polymorphic loci reveal genetic structure of cultivated pears in East Asia. Acta Hort. (ISHS) 1172:107-114
Simple sequence repeat, genetic structure, Asian pear