S02 - Session O4 - II - Assessment of genetic variability amongst cultivated varieties of quince (Cydonia oblonga Mill.) detected by ISSR

Authors: Ana Pedrosa *, Alberto Cardoso , Tércia Lopes, Marlene Mota, Mafalda Resende , Mário Cristóvão, Christophe Espírito Santo , Jorge Canhoto, Sandra Correia

Quince ( Cydonia oblonga Mill.) is an important pome fruit species in the Rosaceae family and one of the most underutilized. It is frequently cultivated for its rootstocks for apple and pear scion cultivars and nutritious fruits. Nowadays, Portugal ranks ninth in its world production (13955 t), with a substantial expansion, particularly as an alternative to traditional cultivations. Cultivar breeding by intraspecific crossing has been very limited, and germplasm resources have been poorly phenotypically characterized. The same is true for molecular characterization through different molecular marker systems. Phenotypic and molecular analyses of C. oblonga 's germplasm are essential for breeding and cultivar inscriptions in plant variety catalogues. This work aimed to investigate the genetic variations within five quince cultivated varieties ('Galega', 'do Portugal', 'Maçã', 'Pera' and 'Champion') in the Beira Interior region in Portugal through Simple Sequence Repeat (SSR) markers. The plant material used was sampled from forty accessions, strategically collected from previously georeferenced orchards in the CULTIVAR project framework (https://icultivar.pt). Productivity data, including fruit quality parameters, was registered for five randomly selected trees for each variety in each orchard. For molecular analysis, young leaf tissues from each cultivar were collected and immediately frozen in liquid nitrogen. Subsequently, NucleoSpin® Plant II (Macherey-Nagel) was used and optimized to perform total genomic DNA extraction. A total of 9 highly polymorphic SSR were chosen and tested for amplification. PCR reactions were optimized in accordance with NZYTaq II 2× Green Master Mix protocol requirements. A phenogram based on genetic similarity was constructed, showing distinct groups that can be correlated with the purposes of fruit production and rootstocks, namely within the 'Galega' variety. SSR was a reliable tool for determining genetic variations between quince varieties.