Genome-wide characterization of simple sequence repeats in Pyrus bretschneideri and their application in an analysis of genetic diversity in pear

Abstract

BackgroundPear (Pyrus spp.) is an economically important temperate fruit tree worldwide. In the past decade, significant progress has been made in pear molecular genetics based on DNA research, but the number of molecular markers is still quite limited, which hardly satisfies the increasing needs of geneticists and breeders.ResultsIn this study, a total of 156,396 simple sequence repeat (SSR) loci were identified from a genome sequence of Pyrus bretschneideri ‘Dangshansuli’. A total of 101,694 pairs of SSR primers were designed from the SSR loci, and 80,415 of the SSR loci were successfully located on 17 linkage groups (LGs). A total of 534 primer pairs were synthesized and preliminarily screened in four pear cultivars, and of these, 332 primer pairs were selected as clear, stable, and polymorphic SSR markers. Eighteen polymorphic SSR markers were randomly selected from the 332 polymorphic SSR markers in order to perform a further analysis of the genetic diversity among 44 pear cultivars. The 14 European pears and their hybrid materials were clustered into one group (European pear group); 29 Asian pear cultivars were clustered into one group (Asian pear group); and the Zangli pear cultivar ‘Deqinli’ from Yunnan Province, China, was grouped in an independent group, which suggested that the cultivar ‘Deqinli’ is a distinct and valuable germplasm resource. The population structure analysis partitioned the 44 cultivars into two populations, Pop 1 and Pop 2. Pop 2 was further divided into two subpopulations. Results from the population structure analysis were generally consistent with the results from the UPGMA cluster analysis.ConclusionsThe results of the present study showed that the use of next-generating sequencing to develop SSR markers is fast and effective, and the developed SSR markers can be utilized by researchers and breeders for future pear improvement.Electronic supplementary materialThe online version of this article (10.1186/s12864-018-4822-7) contains supplementary material, which is available to authorized users.

Detection and application of genome-wide variations in peach for association and genetic relationship analysis

“…Frequency analysis of various nucleotide repeats of SSRs in the peach genome revealed that mononucleotides were the most abundant SSR (47.36% of the total), followed by di-, tri-, etc (Table 4). However, tetranucleotide repeats were the primary motif in cucumber [24], Chinese jujube [19] and pear [26] and the most abundant in soybean [27] and rice [28]. Among the dinucleotide repeats in peach, AT/TA was the most common, followed by CT/TC (Table 4).…”

Detection and application of genome-wide variations in peach for association and genetic relationship analysis

“…Frequency analysis of various nucleotide repeats of SSRs in the peach genome revealed that mononucleotides were the most abundant SSR (47.36% of the total), followed by di-, tri-, etc (Table 4). However, tetranucleotide repeats were the primary motif in cucumber [37], Chinese jujube [33] and pear [39] and the most abundant in soybean [40] and rice [41]. Among the dinucleotide repeats in peach, AT/TA was the most common, followed by CT/TC (Table 4).…”

Chromosome level high-density integrated genetic maps improve the Pyrus bretschneideri ‘DangshanSuli’ v1.0 genome

“…The tens of thousands of hybrid trees required for breeding occupy a large area of land for many years and consume significant manpower and financial resources. Molecular marker-assisted selection (MAS) based on Quantitative Trait Locus (QTL) mapping of important agronomic traits allows breeders to screen hybrids at the seedling stage and eliminate those lacking potential [ 4 , 6 ]. Thus, this practice can reduce the land, labor and financial investment required for crop breeding, especially for perennial fruit trees [ 4 ].…”