关键词: 梨, 种质, 叶绿体DNA, 遗传多样性, 演化分析

Abstract: In this study we investigated 5 chloroplast DNA non-coding regions trnL-trnF-1，trnL-trnF-2，trnS-psbC，accD-psaI，rps16-trnQ and one gene rbcL of pear（Pyrus L.）accessions originated from southern area of Qinling Mountain–Huaihe River line to detect the evolutionary relationship and genetic diversity. The aligned length of combined fragment of 188 pear accessions was 5 612 bp（InDels included）. A total of 13 haplotypes，4 singleton variable sites，16 parsimony informative sites and 14 InDels were recognized after sequencing analysis，and the haplotype diversity（Hd）and nucleotide diversity （Pi）were 0.7178 and 0.35 × 10-3，respectively. Among the chloroplast DNA regions studied，the highest Hd value 0.7177 was detected in the accD-psaI intergenic spacer and the lowest one 0.0317 was found in rbcL gene region. Twelve haplotypes were identified in 162 pear accessions originated from southern area of Qinling–Huaihe line and their haplotype diversity（Hd）and nucleotide diversity（Pi）were 0.713 and 0.29 × 10-3，respectively. In geography distribution of pears，the highest Hd value（0.889）was detected in 10 accessions from Hunan Province and the lowest one（0）was found in 8 accessions from Guizhou Province. Eight haplotypes were identified in 138 Chinese Sand Pear accessions，of which 3 common cpDNA haplotypes H2，H4 and H5 were shared by 130 Chinese Sand Pear and 37 Chinese White Pear ones and 5 rare cpDNA haplotypes H6，H10，H11，H12 and H13 were detected in 8 Sand Pear local accessions‘Qingpizhong’，‘Tianxiaoli’，‘Xihua Hongli’，‘Huiyang Hongli’，‘Shexiangli’，‘Tanghuqing’，‘Hongfen’and‘Hengxian Jinpaoli’. The Median-joining Network showed H6 and H11 were the ancestral cpDNA haplotypes，whereas H1，H4 and H5 were the advanced ones. A close genetic relationship between P. pyrifolia and P. bretschneideri from southern area of Qinling–Huaihe line and high genetic diversity of the local cultivated sand pears from Hunan Province could be inferred based on chloroplast DNA variation information.

Key words: pear, germplasm, chloroplast DNA, genetic diversity, phylogenetic relationship