Abstract:
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The sand pear (Pyrus pyrifolia Nakai) is an important fruit crop in China. In this study, simple sequence repeats (SSRs) were used to estimate the level and pattern of genetic diversity among 233 sand pear landraces collected from 10 different geographic regions in China. The results demonstrated that the SSR technique is an effective tool for assessing genetic diversity and the geographic pattern of genetic variation among sand pear landraces of different origins. A total of 184 putative alleles was detected using 14 primer pairs with an average of 13.1 alleles per locus. The mean expected heterozygosity and observed heterozygosity across all loci were 0.705 and 0.671, respectively. High genetic diversity was found in all populations except for that originated from Jiangxi (A(e) = 3.149; H-e = 0.655), whereas at the regional level, those from central China were less diverse than those from other regions. Analysis of molecular variance showed that most genetic differences resided among landraces within populations. Additionally, un-weighted pair group with arithmetic average clustering and principal component analysis plotting based on Nei's genetic distance revealed distinct gene pools in agreement with geographic distribution.