Structural and Comparative Analysis of the Complete Chloroplast Genome of Pyrus hopeiensis-"Wild Plants with a Tiny Population"-and Three Other Pyrus Species.

Yongtan Li,Minsheng Yang,Jintao Xu,Longfei Li,Lijuan Gao,Jun Zhang

doi:10.3390/ijms19103262

Yongtan Li, Minsheng Yang + Show 4 more

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https://doi.org/10.3390/ijms19103262

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Abstract

Pyrus hopeiensis is a valuable wild resource of Pyrus in the Rosaceae. Due to its limited distribution and population decline, it has been listed as one of the “wild plants with a tiny population” in China. To date, few studies have been conducted on P. hopeiensis. This paper offers a systematic review of P. hopeiensis, providing a basis for the conservation and restoration of P. hopeiensis resources. In this study, the chloroplast genomes of two different genotypes of P. hopeiensis, P. ussuriensis Maxin. cv. Jingbaili, P. communis L. cv. Early Red Comice, and P. betulifolia were sequenced, compared and analyzed. The two P. hopeiensis genotypes showed a typical tetrad chloroplast genome, including a pair of inverted repeats encoding the same but opposite direction sequences, a large single copy (LSC) region, and a small single copy (SSC) region. The length of the chloroplast genome of P. hopeiensis HB-1 was 159,935 bp, 46 bp longer than that of the chloroplast genome of P. hopeiensis HB-2. The lengths of the SSC and IR regions of the two Pyrus genotypes were identical, with the only difference present in the LSC region. The GC content was only 0.02% higher in P. hopeiensis HB-1. The structure and size of the chloroplast genome, the gene species, gene number, and GC content of P. hopeiensis were similar to those of the other three Pyrus species. The IR boundary of the two genotypes of P. hopeiensis showed a similar degree of expansion. To determine the evolutionary history of P. hopeiensis within the genus Pyrus and the Rosaceae, 57 common protein-coding genes from 36 Rosaceae species were analyzed. The phylogenetic tree showed a close relationship between the genera Pyrus and Malus, and the relationship between P. hopeiensis HB-1 and P. hopeiensis HB-2 was the closest.

Highlights

Pyrus belongs to the Pyrus ssp. of the Maloideae subfamily (Rosaceae), which mainly includes temperate fruit trees
There was little difference in length between the two P. hopeiensis genotypes, and what difference existed was in the large single copy (LSC) region
The results showed that the size, structure, sequence, and GC content of the chloroplast genome of P. hopeiensis were similar to those of the other three Pyrus species, which was characteristic of the slow evolution of the genus Pyrus [7] in comparison to the chloroplast genomes of P. hopeiensis, P. communis L. cv

Summary

Introduction

Pyrus belongs to the Pyrus ssp. of the Maloideae subfamily (Rosaceae), which mainly includes temperate fruit trees. Of the Maloideae subfamily (Rosaceae), which mainly includes temperate fruit trees. There are more than 30 species in this genus, and 13 species are present in China [1,2]. The pear has been cultivated for over 3000 years in China. It is the third most commonly cultivated fruit tree after apple and citrus. China is the world’s largest pear producer, accounting for 71.2% of the world’s total pear area. Wild resources of Pyrus are extremely precious. They are mostly distributed in the valleys, hillsides, and forest margins, and are characterized by cold resistance, drought resistance, disease resistance, barren tolerance, saline–alkali tolerance, and strong adaptability

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