Assessment of genetic diversity and fingerprinting of strawberry genotypes using inter simple sequence repeat marker

Abstract

Ability of a plant species to respond adaptively to environmental challenges depends on its genetic diversity.1 Strawberry is an economically and commercially important horticultural crop with rich source of bioactive compounds that are beneficial to human health.2 It has been reported that strawberry fruits, because of its high levels of vitamin C and K, folate, phenolic compounds and flavonoids, retards age-related effects on memory.3 Fruits of this horticultural crop are widely consumed fresh or in processed forms, such as jams, juices, and jellies. Strawberry fruits also has shown antioxidant and anti-cancer properties by inhibiting production of Reactive Oxygen Species (ROS) and carcinogens reduction.4–6 The diversity and high properties value of its compounds make strawberry a very attractive fruit for studying. Wild strawberry species as genetic resources are valued by breeders to produce new varieties with novel traits that are more productive, more nutritious, more market-friendly and more resistant to biotic (viruses, fungi, bacteria, weeds, insects and pests) and abiotic (drought, salinity, cold, heat) stresses. There are several systems such as morphological, chemical, and biochemical markers for evaluating diversity levels in plants. But these systems of classification are influenced by factors like temperature, humidity, light and/or plants ages which can modify results of classification. While, DNA-based marker systems provide a reliable and powerful tools for assessing differences between organisms with simultaneous elimination of the other systems constraints and are increasingly used in breeding programs and germplasm management of many horticultural crops. Several PCR (polymerase chain reaction)based DNA marker systems including RAPD (random amplified polymorphic DNA), AFLP (amplified fragment length polymorphism) and SSRs (simple sequence repeats or microsatellites) are available for genetic assessment,7 but each of the methods have some limitations: low primer annealing temperature and reproducibility for RAPD, requirement for prior sequence information from flanking regions to develop primers for SSR and high experiment costs for AFLP. ISSR marker is a cheap, fast and simple genotyping technique based DNA that requires small amounts of DNA template.8 This marker is more reliable than RAPD because of longer length of primers and high annealing temperature and ISSR does not requires any prior sequence information. ISSR marker uses a single primer targeting microsatellite motifs that generates abundant polymorphic bands with a reliable and reproducible banding patterns in many systems.7,9,10 ISSR marker has been used successfully to assess genetic variation in a vast range of plants and horticultural crops including blueberry,11 lingo berry,12 citrus,13 potato,14 Oryza15 and described as a powerful technique to assess genetic diversity to detect similarities between and within species levels. It is well know that availability and deep knowledge of genetic diversity of any given crop will enhance extent of any improvements.16 Strawberry belongs to Rosaceae family, which has approximately 3000 members,17 Fragaria genera and six species all iedentifies as straswery. Strawberry has different size, color, taste, form, season of ripening, level of fertility and resistance to disease.18 One of the most important habitats for wild strawberries genotypes