Diversity of Wild Pyrus communis Based on Microsatellite Analyses

Abstract

<jats:p>Edible european pears (<jats:italic>Pyrus communis</jats:italic> L. ssp. <jats:italic>communis</jats:italic>) are derived from wild relatives native to the Caucasus Mountain region and eastern Europe. Microsatellite markers (13 loci) were used to determine the relationships among 145 wild and cultivated individuals of <jats:italic>P. communis</jats:italic> maintained in the National Plant Germplasm System (NPGS). A Bayesian clustering method grouped the individual pear genotypes into 12 clusters. <jats:italic>Pyrus communis</jats:italic> ssp. <jats:italic>caucasica</jats:italic> (Fed.) Browicz, native to the Caucasus Mountains of Russia, Crimea, and Armenia, can be genetically differentiated from <jats:italic>P. communis</jats:italic> ssp. <jats:italic>pyraster</jats:italic> L. native to eastern European countries. The domesticated pears cluster closely together and are most closely related to a group of genotypes that are intermediate to the <jats:italic>P. communis</jats:italic> ssp. <jats:italic>pyraster</jats:italic> and the <jats:italic>P. communis</jats:italic> ssp. <jats:italic>caucasica</jats:italic> groups. Based on the high number of unique alleles and heterozygosity in each of the 12 clusters, we conclude that genetic diversity of wild <jats:italic>P. communis</jats:italic> is not fully represented at the NPGS. Additional diversity may be present in seed accessions stored in the NPGS and more pear diversity could be captured through supplementary collection trips to eastern Europe, the Caucasus Mountains, and the surrounding countries.</jats:p>

Genetic diversity and structure of Pyrus accessions of Indian Himalayan region based on morphological and SSR markers

“…An average of 9.5 alleles per primer pair observed was higher than previous studies in pear by Nishitani et al (2009) and Wolko et al (2010) while it was lower than the study conducted by Volk et al (2006) in wild P. communis. Similarly, mean heterozygosity and PIC of 0.81 and 0.80, respectively, were higher than in the studies detected by other workers (Bao et al 2007;Wünsch and Hormaza 2007;Nishitani et al 2009;Wolko et al 2010) in different pear varieties.…”

Genetic diversity and structure of local apple cultivars from Northeastern Spain assessed by microsatellite markers

“…cultivars), since the assemblage of these materials cannot be strictly regarded as biological populations even if collected within a small area. As a consequence, Bayesian inference has become a powerful tool to assess the genetic structure in tree species such as pear (Ferreira dos Santos et al 2011;Iketani et al 2010;Miranda et al 2010;Volk et al 2006), plum (Horvath et al 2011), sweet cherry (Mariette et al 2010), olive (Breton et al 2008;Erre et al 2010) and chestnut (Pereira-Lorenzo et al 2010). In apple, it has been mainly used to reveal genetic structure and relationships in wild Malus species such as Malus sieversii ), Malus orientalis ) and Malus sylvestris (Coart et al 2003;Larsen et al 2006), but studies evaluating structure within cultivated apple material remain scarce (Pereira-Lorenzo et al 2008).…”

Comparative morphometric study and relationships between the Caucasian species of wild pear (Pyrus spp.) and local cultivars in Georgia

“…and P. pyraster (L.) Burgsd. are regarded as the main wild ancestors from which the cultivated European pear (P. communis L.) has probably evolved (Zohary and Hopf, 2000;Volk et al, 2006;Yamamoto and Chevreau, 2009). P. caucasica ('Panta' in Georgian) is an endemic species of the Caucasus (Kuthateladze, 1980;Brezhnev and Korovina, 1981).…”

“…P. caucasica ('Panta' in Georgian) is an endemic species of the Caucasus (Kuthateladze, 1980;Brezhnev and Korovina, 1981). Its occurrence outside of the Caucasus region (Volk et al, 2006;Yamamoto and Chevreau, 2009) might be explained by planting of this tree in Soviet time in orchards and forest gardens for producing vegetative and generative rootstocks for fruit trees (Sokolov et al, 1980). Originally, it is distributed in natural habitats of broad-leaved and mixed coniferous forests at low, middle and upper montane belts (500-1800 m a.s.l.)…”

“…Genetically it is differentiated from P. pyraster which is native to Eastern and Central European countries, the Balkan Peninsula and Turkey. However, both species show close genetic relations to domesticated pears (Volk et al, 2006). This situation put us into the idea to compare P. cauacsica with local Georgian cultivars of pear and reveal relationships between them.…”