117 MOLECULAR MARKERS USAGES IN CULTIVATED FRUIT TREES FROM ROSACEAE FAMILY Mihaela IORDĂCHESCU 1 , Anca Amalia UDRIȘTE 1 , Liliana BĂDULESCU 1, 2 1 Research Center for Studies of Food Quality and Agricultural Products, University of Agronomic Sciences and Veterinary Medicine of Bucharest, 59 Mărăști Blvd, District 1, Bucharest, România 2 University of Agronomic Sciences and Veterinary Medicine of Bucharest, Faculty of Horticulture, 59 Mărăști Blvd, District 1, Bucharest, România Corresponding author email: amalia.udriste@qlab.usamv.ro Abstract Most fruit tree species cultivated in Romania, such as apple, pear, plum, peach, apricot, cherry, as well as some berry species such as blackberry, raspberry and strawberry belong to the Rosaceae family. As most of these species are woody perennials, the traditional methods of creating new varieties are taking much longer time than in the case of annual species. New methods and tools based on the recent discoveries in molecular genetics are being developed in order to shorten the time needed to create new commercial varieties. Molecular markers, specific DNA regions linked to genes responsible for various traits (color, shape, taste, resistance/tolerance to biotic and abiotic stresses, etc.) are some of the tools used in genotype-assisted breeding programs. This review sums up the main results of studies on molecular markers regarding cultivated fruit tree species of Rosaceae family with commercial importance. Key words: molecular markers, Rosaceae, Malus, Prunus, molecular breeding. INTRODUCTION Rosaceae family consists of 91 genera and 2,950 species (Christenhusz and Byng, 2016). Most cultivated fruit species from Romania belong to this family. These species are important not only in alimentation, but also as ornamentals. Recent sequencing techniques and genomes sequencing brought up new data that can be used for a variety of purposes, such as identification and characterization of genes responsible for agronomically important traits, genotyping by sequencing, marker assisted selection, identification of molecular markers linked to the traits of interest (Soundararajan et al., 2019). Molecular markers such as Single Nucleotide Polymorphism (SNP), Random Amplification of Polymorphic DNA (RAPD), Restriction Fragment Length Polymorphism (RFLP), Amplified Fragment Length Polymorphism (AFLP), Simple Sequence Repeats (SSR), Inter Simple Sequence Repeats (ISSR), Cleaved Amplified Polymorphic Sequence (CAPS), Sequence-Related Amplified Polymorphism (SRAP), Sequence Characterized Amplified Region (SCAR), can be used as tools for genetic and physical mapping of genomes, the identification of genes controlling various processes and phenotypes (trait association), genetic diversity and evolutionary analyses, and in marker- assisted breeding for crop improvement. Single Sequence Repeats (SSRs) are molecular markers that have been used extensively for genotyping commercial crops, as they are multiallelic, highly polymorphic, they have high discriminatory potential and good reproducibility, and can detect polyploidy (Nybom and Lācis, 2021). Within the Rosaceae family, multiple SSR markers have been developed for most cultivated species. To improve comparison among different studies, European Cooperative Programme for Plant Genetic Resources (ECPGR; www.ecpgr.cgiar.org) published recommended SSR loci sets for apple, pear, cherry and plum (Nybom and Lācis, 2021). SSR markers may be used to discriminate between different genotypes of the same species and frequently those of closely related species, so they are used frequently in variability studies, fingerprinting and map construction. Mnejja et al. (2010) studied 145 Rosaceae SSR primer Scientifc Papers. Series B, Horticulture. Vol. LXV, No. 1, 2021 Print ISSN 2285-5653, CD-ROM ISSN 2285-5661, Online ISSN 2286-1580, ISSN-L 2285-5653