Detection of somaclonal variation in plants regenerated from different tissues of strawberry (Fragaria x ananassa) using ISSR marker

Production of genetically and phenotypically stable plantlets is the main purpose in commercial strawberry tissue culture. In this study, different tissues of Fragaria ananassa cv. Camarosa including stipule, apical meristem, leaf and petiole were cultured in Murashige and Skoog (MS) medium supplemented with different concentrations of N6-benzyladenine (BA) (0.5, 1, 2, 3 mg/L) and indole-3-butyric acid (IBA) (0.1 and 0.5 mg/L). For apical meristem explants, the best regeneration rate (7.6 shoots per each explant) was obtained in the medium containing 1 mg/L BA and 0.1 mg/L IBA. Whereas stipule explants showed the highest regeneration rate in the medium containing 2 mg/L BA and 0.1 mg/L IBA. For leaf and petiole explants, the medium containing 2 mg/L BA and 0.5 mg/L IBA had the best hormonal combination. To determine the genetic variation, micropropagated plants from different tissue (after 8 subcultures) were analyzed by the inter-simple sequence repeats (ISSR) molecular marker. Among the 18 pre-selected primers, 10 displayed clear, reproducible and informative bands. A total of 88 distinct bands with a polymorphic rate of 46% were produced in the molecular profile of different explants. The highest and the lowest similarity values to maternal plants belonged to stipule and petiole explants with a similarity index of 0.738 and 0.645, respectively. Vitroplants derived from stipule and apical meristem showed the highest genetic stability with respect to maternal plants. With respect to genetic stability and regeneration rate, apical meristem can be recommended as suitable explants with the highest genetic fidelity. The findings of this study could be applied for commercial scale multiplication of strawberry, and also demonstrate that ISSR markers are eligible for detection of somaclonal variations.