Egypt. J. Plant Breed. 21(1):1 – 12 (2017) EFFECT OF BENZYLAMINOPURINE CONCENTRATION AND NUMBER OF SUBCULTURES ON BEHAVIOR OF SOME STRAWBERRY CULTIVARS IN VITRO S.F. EL-Sayed 1 , A.M. EL-Sawy 2 , Sahar S. Taha 1 , Manal Sh. Gomah 3 1. Vegetable Crops, Fac. Agric., Cairo University, Giza, Egypt- 2. Plant Biotechnology Dept., National Res. Center, El-Behoos St, Dokki, Giza, Egypt 3. PICO Company, Giza, Egypt ABSTRACT This study was conducted was the Plant Tissue Culture Laboratory of PICO Comp., Giza, Egypt, during the period of 2010-2014. Meristem tips of three strawberry (Fragaria x ananassa) cultivars, namely Sweet Charlie, Festival and Camarosa were excised and cultured on multiplication MS medium containing 0.50, 0.25or 0.10 mg/l BAP. Subculture was carried every four week intervals till sixth subculture. Camarosa cv. exhibited significant higher multiplication rate than the other two cultivars; i.e. Sweet Charlie and Festival. The sixth subculture showed the highest multiplication rate (3.6, 3.4 and 3.26 in cvs Sweet Charlie, Festival and Comarosa, respectively). The number of shoots per explant at different concentration of BAP was varied depending on the cultivar and number of subcultures. Molecular analysis by using RAPD-PCR indicated that mass propagation via meristem tip culture till the sixth subculture is reliable in producing genetically similar plants to the mother ones. Key words: Strawberry, BAP, Micropropagation, Subculture, Molecular analysis, RAPD-PCR. INTRODUCTION Strawberry has been becoming one of the major vegetable crops in Egypt for fresh fruit consumption, processing and export. The cultivated area was doubled through the past years; reaching 13888.1 Feddan in 2011 with production of 242297 tons (FAO 2012).This expansion required the availability of pathogen-free transplants depending on the introduction of modern micropropagation systems. Traditionally, strawberry plants are propagated by runners derived from unclear stock materials via shoot tip culture (Boxus 1974, 1977 and Reinetrt and Bujaj 1977). Micropropagation of strawberry offers a number of advantages. Many researchers have reported increased vigor and runner production in tissue-culture derived strawberry plants. This response in temporary, usually observed only in the tissue culture propagated plants and the first runners, but is very advantageous to the nursery producer (Swartz et al 1981 and Cameron and Hancock 1986). The second advantage is the ability to rapidly multiply new cultivars. More than one million plants can be micropropagated from a single meristem tip in a year. In addition, micropropagation allows rapid and flexible production of healthy, high- quality strawberry plants which are usually true-to-type (Hughes 2002). In vitro techniques also are important tools for modern plant improvement