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Pears (Pyrus spp.) are one of the most important fruit crops in temperate regions and are self-incompatible. Large numbers of interspecific hybrids occur naturally and, have been artificially produced in breeding programs. Also, many pear cultivars were generated from intraspecific crossing. Some varieties have been cultivated for a long time, but their breeding history remains unknown. The P. pyrifolia cv. Niitaka is one of key varieties in the Korean pear breeding program. Therefore, its complete chloroplast (cp) genome was determined, and its phylogenetic relationships with other Pyrus species and P. pyrifolia cultivars were addressed. The cp genome has a total of 133 genes, including 93 protein-coding genes, 32 tRNA genes, and eight rRNA genes. We found many SNPs in the 'Niitaka' cp genes when compared with that in another Korean cultivar 'Wonwhang' (BioSample SAMN05196235). The primer sets for six genes that had two or more SNPs in their sequence were used to amplify and sequence 27 Pyrus and one Malus cultivars. Of these, we found dramatic InDel polymorphisms in the ndhA and clpP genes. Phylogenetic relationships using the sequences of these two genes in 28 samples showed that they could mainly be classified into two groups of P. pyrifolia. Group I constitutes Niitaka and all cultivars that contain chloroplast maternally inherited from Niitaka, and group II constitutes the other cultivars of P. pyrifolia. We have developed a useful polymorphic molecular marker to confirm the maternal parent in the interspecific hybrids of Niitaka and previous mothers of Niitaka, (such as Amanogawa). Furthermore, these two genes could identify and greatly aid in understanding the subspecies classification in Pyrus. [ABSTRACT FROM AUTHOR]

The complete chloroplast genome of Wonwhang (BioSample SAMN05196235), Pyrus pyrifolia, was assembled and analyzed by de novo assembly using whole-genome sequencing data. The accession NC_015996 was used as a reference sequence in this study. The total chloroplast genome size of the Wonwhang was 159,922 bp in length, including a pair of inverted repeat regions (IRs) of 26,392 bp that are separated by a large single-copy region of 72,023 bp and a small single-copy region of 19,235 bp. A total of 132 genes, including 93 protein-coding genes, 31 tRNA genes and eight rRNA genes, were predicted from the chloroplast genomes. Among them, 18 genes occur in IRs, containing nine protein-coding genes, five tRNA genes and four rRNA genes. The GC content of Wonwhang chloroplast genome is 36.6%. The phylogenetic analysis with nine Rosids species and three other species revealed that Wonwhang was clustered with Malus genus. [ABSTRACT FROM AUTHOR]