Elucidating the contribution of wild related species on autochthonous pear germplasm: A case study from Mount Etna

PLoS One. 2018 Jun 1;13(6):e0198512. doi: 10.1371/journal.pone.0198512. eCollection 2018.

Abstract

The pear (genus Pyrus) is one of the most ancient and widely cultivated tree fruit crops in temperate climates. The Mount Etna area claims a large number of pear varieties differentiated due to a long history of cultivation and environmental variability, making this area particularly suitable for genetic studies. Ninety-five pear individuals were genotyped using the simple sequence repeat (SSR) methodology interrogating both the nuclear (nDNA) and chloroplast DNA (cpDNA) to combine an investigation of maternal inheritance of chloroplast SSRs (cpSSRs) with the high informativity of nuclear SSRs (nSSRs). The germplasm was selected ad hoc to include wild genotypes, local varieties, and national and international cultivated varieties. The objectives of this study were as follows: (i) estimate the level of differentiation within local varieties; (ii) elucidate the phylogenetic relationships between the cultivated genotypes and wild accessions; and (iii) estimate the potential genetic flow and the relationship among the germplasms in our analysis. Eight nSSRs detected a total of 136 alleles with an average minor allelic frequency and observed heterozygosity of 0.29 and 0.65, respectively, whereas cpSSRs allowed identification of eight haplotypes (S4 Table). These results shed light on the genetic relatedness between Italian varieties and wild genotypes. Among the wild species, compared with P. amygdaliformis, few P. pyraster genotypes exhibited higher genetic similarity to local pear varieties. Our analysis revealed the presence of genetic stratification with a 'wild' subpopulation characterizing the genetic makeup of wild species and the international cultivated varieties exhibiting the predominance of the 'cultivated' subpopulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • DNA, Plant / chemistry
  • DNA, Plant / genetics
  • DNA, Plant / metabolism
  • Gene Frequency
  • Genetic Variation
  • Genotype
  • Haplotypes
  • Microsatellite Repeats / genetics*
  • Phylogeny
  • Principal Component Analysis
  • Pyrus / classification
  • Pyrus / genetics*

Substances

  • DNA, Plant

Grants and funding

The authors declare the study was supported by internal funding of Department of Agriculture, Food and Environment of Catania University, Catania, Italy. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.