Genetic Pool of the Cultivated Pear Tree (Pyrus spp.) in the Canary Islands (Spain), Studied Using SSR Molecular Markers

Abstract

The Canary Islands have an enormous richness of crops and varieties, many of them traditional or local, selected for decades by farmers based on the most desirable characteristics. Pear trees were introduced to the Canary Islands presumably in the first years after their Conquest in the 15th century, reaching a high degree of diversification. In this study, to determine the genetic identity of the genus Pyrus in the Canary Islands for conservation purposes, 266 pear accessions from the islands of Tenerife, La Palma and Gran Canaria were characterized with 18 SSRs, in addition to 190 genotypes from Galicia, Asturias, wild and commercial varieties as references to detect possible synonyms, genetic relationships and the possible genetic structure. We identified 310 unique genotypes, both diploid and putative triploid, 120 of them present only in the Canary Islands (39%, with 50% clonality). The population structure of the genotypes was analyzed by STRUCTURE 2.3.4 software (Pritchard Lab, Stanford University, Stanford, CA, USA). The dendrogram, by using the Jaccard coefficient and principal component analysis (PCoA), separated the analyzed genotypes into stable groups. One of these groups was formed only by Canarian varieties present at lower altitudes, showing adaptation to low chilling requirements with a significant positive correlation (0.432, p < 0.01). This first study of the pear germplasm in the Canary Islands reflects the importance of the group of local cultivars and their need for conservation given they are adapted to their peculiar climatic conditions and have a low number of chill units.

Management of genetic erosion: The (successful) case study of the pear (Pyrus communis L.) germplasm of the Lazio region (Italy)

“…An additional locus (CH01d03) was chosen due to its high PIC value. However, by performing a meta-analysis of the main European studies conducted in the last 20 years in pear, we found that only a few studies ( dos Santos et al., 2011 ; Urrestarazu et al., 2015 ; Bielsa et al., 2021 ; Velázquez-Barrera et al., 2022 ) rigorously followed the proposed SSR list ( Table 3 ). Among the SSR loci, the most frequently adopted were CH01d09, CH01f07a, EMPc11, CH04e03 and CH02b10.…”

Genetic Diversity Analysis and Core Germplasm Collection Construction of Camellia oleifera Based on Fruit Phenotype and SSR Data

“…These differences may be because the samples used in this study were collected from different geographical origins, and the fruit traits were influenced by both genes and the environment, leading to natural variations in morphology, physiology, structure, and gene expression [ 42 ]. It may also be related to the number of SSR primers; Velázquez-Barrera et al studied the population structure of 118 cultivated pear trees using 12 SSRs and 18 SSRs, they found different results of population structure when they eliminated the higher percentile of null alleles and linked loci [ 43 ]. The results showed that SSR primers have a substantial influence on classification.…”

SSR‐based DNA fingerprinting of fruit crops

“…LGs are reported according to the GDR database (Liu et al, 2015;Urrestarazu et al, 2015;Velázquez-Barrera et al, 2022).…”

“…A reference genotype was not available; a genome assembly was not available or was not assembled in chromosomes or linkage groups. Velázquez- Barrera et al, 2022). All are included in the list suggested by Evans et al (2009) and were previously agreed as being suitable by the European Cooperative Programme for Plant Genetic Resources.…”

“…The second part of the list includes 12 markers that are also frequently used in the literature for fingerprinting both European and Asian pears (Baccichet et al., 2020; Bennici et al., 2018; Liu et al., 2015; Montanari et al., 2020; Sehic et al., 2012; Urrestarazu et al., 2015; Velázquez‐Barrera et al., 2022). All are included in the list suggested by Evans et al.…”