Journal of American Science, 2012; 8(5) http://www.americanscience.org 41 Molecular Genetic Evaluation Of Seven Varieties Of Summer Squash El-Adl, A.M.; 1 A.H. Abd El-Hadi; 1 Horeya M. Fathy 2 and M.A. Abdein 2 1 Dept. of Genetics, Faculty of Agric. Mansoura University, Egypt. 2 Vegetables Breeding Department, Horticulture Res. Inst. (HRI), ARC, Giza, Egypt. Corresponding author: abdeingene@yahoo.com ABSTRACT: The present investigation was carried out in 2010 growing season, with the aim of molecular genetic evaluation of seven squash parents under Egyptian conditions. The study included seven squash varieties. These selected squash parents were: i.e. Eskandrani (P 1 ), Zucca Patisson custard white (P 2 ), All Green Bush (P 3 ), Courgette Orelia (P 4 ), Sakiz (P 5 ), Copi (P 6 ) and Gapla (P 7 ). These parents were discriminated by their leaves fingerprints as obtained through protein electrophoresis technique and RAPD-PCR technique using five random primers. Protein electrophoresis successfully generated reproducible polymorphic banding patterns. The generated profiles revealed high levels of polymorphism among the studied parents. Data of the analysis recorded a sum of 18 bands. These bands were identified as 11 polymorphic bands and 7 monomorphic ones in all studied parents. The polymorphic bands were scored as 3 unique bands. These unique bands were used to discriminate between the seven squash parents. Five 10-mer arbitrary primers of twenty-one of each RAPD successfully generated reproducible polymorphic products. The generated profiles revealed high levels of polymorphism among the studied parents. Data of these primers recorded a sum of 51 bands. These bands were identified as 29 polymorphic bands and 22 monomorphic ones in all parents under study. The polymorphic bands were scored as 8 unique bands. These unique bands were used to discriminate between the seven squash parents. In addition, the results generated from protein and RAPD profiles were pooled together to elucidate the genetic relationships among the seven examined parents. The constructed dendrogram tree divided the studied parents into two major groups. The first group included Gapla (P 7 ) only, while the second group was divided into two main sub groups, the first main sub group was divided into two main sub sub groups the first main sub sub group included All Green Bush (P 3 ) and Courgette Orelia (P 4 ). The second main sub sub group included Sakiz (P 5 ) and Copi (P 6 ). On the other hand, the second main sub group included Eskandrani (P 1 ) and Zucca Patisson custard white (P 2 ) parents. From the foregoing results, using protein and RAPD markers for characterization and construction of genetic linkage maps and the molecular genetic diversity of parents support the use of marker-assisted selection (MAS) in squash cultivars breeding programs. [El-Adl, A.M.; A.H. Abd El-Hadi; Horeya M. Fathy and M.A. Abdein. Molecular Genetic Evaluation Of Seven Varieties Of Summer Squash. Journal of American Science 2012; 8(5):41-48] (ISSN: 1545-1003). http://www.americanscience.org . 5 Keyword: Cucurbitaceae, summer squash, varieties, protein, DNA, RAPD-PCR. 1.INTRODUCTION Cucurbitaceae is one of the most important botanical families for human use as favorable vegetable crop. Thus, summer squash (Cucurbita pepo, L.) is considered to be one of the most popular vegetable crops grown in Egypt. It is known as a vegetable marrow and is called also Kosa by the Egyptian. In Egypt, there are only two local cultivars of squash i.e. Balady, which is lately discarded for its prostrate growth habit and low yield and Eskandarani, which is high yielding and satisfies both the producer and consumer. The past limitation associated with pedigree data and morphological, physiological and cytological markers for assessing genetic diversity in cultivated and wild plant species have largely been circumvented by the development of DNA markers such as random amplified polymorphic DNAs (RAPD). This method was proved to be useful for germplasm identification, elucidation of genetic relationships of numerous plant cultivars and species, Williams et al., (1990); Halward et al.,( 1992) and Levi and Rowland (1997). Also, such technique is simple to use and does not require the use of radioactive materials as well as it enables to detect a significant degree of polymorphism. The generated DNA polymorphism reflects both the distance between two annealing sites and the pattern of their distribution throughout the genome of a particular cultivar or species,Williams et al., (1990). Randomly Amplified Polymorphic DNA analysis (RAPD) could be used to identify many useful polymorphisms quickly and efficiently, and as such, it has a tremendous potential for use in cultivar identification. RAPD analysis has been also used to study genetic relationships in a number of fruit trees as almond ,Bartolozzi et al., (1998) plum varieties, Ortiz et al., (1997) peach varieties,Chaparro et al., (1994); Warburton and Bliss( 1996) peach rootstocks ,Lu et al., (1996) and Casas et al., (1999). RAPD markers have been used in peach genetics and breeding programs