IDENTIFICATION OF MALE SPECIFIC MOLECULAR MARKERS IN DATE PALM SEWI CULTIVAR

Abstract

The date palm (Phoenix dactylifera L.) is a monocotyledoneus woody by Giza governorate that cultivate 0.525 millions tree. (Ministry of Agriculture, perennial tree belongs to the Arecaceae family, which comprises 200 genera and more than 2500 species (McCurrach, 2009). In the date palm, the dioecious 1960). Date-palm (2n=36), cultivated mainly in North Africa and Middle East, has major economic, social and environmental importance. Date-palms constitute the principal financial resource and food source of oasis growers, and it contributes to the development of subjacent cultures (alfalfa, fig trees, pepper, tomato, saffron, etc.). In Egypt, date palm trees are classified according to their fleshiness into three classes. The first class is the soft date such as Zaghloul, Samani, and Hayany. The second class is the semidry date such as Sewi, Aglany and Amry. The third class is the dry date like Sakoty and Malkaby. Sewi cultivar, a semi dry date palm, is considered one of the most important commodity items for export in Egypt. It is stored and processed throughout the year. The number of fruitful Sewi female palms in Egypt is 1.834 million. El-Wadi El-Gadid governorate cultivates the biggest number in Egypt, 0.661 million, followed mode (separate male and female individuals) and the late initial reproductive age (5-10 years) are major practical constraints for genetic improvement. Early selection on young seedlings could enhance breeding programmes and generate experimental male and female genetic stocks, but no easy robust cytogenetic protocol exists for sex determination in an immature date palm (Siljak-Yakovlev et al., 1996). Genotype identification and cultivar identification, based on morphological character of date palm, is an intricate empirical exercise (Al-Khalifha et al., 2011). The development of the PCR-based fingerprinting techniques such as randomly amplified polymorphic DNAs (RAPDs) (Welsh and McClelland, 1990; Williams et al., 1990), amplified fragment length polymorphisms (AFLPs) (Lin and Kuo, 1995) and simple sequence repeats (SSRs) (Powell et al., 1996) has accelerated the detection of distinct markers in plant genomes. RAPD method is straightforward and does not require previous genetic knowledge of the target organism. Furthermore, it is very quick and convenient to perform. The RAPD technique has been employed to develop sex-linked markers in Silene latifolia (Zhang et al., 1998), P. longum (Banerjee et al., 1999), Pistacia vera (Hormaza et al., 1994), Salix viminalis (Alstrom-Rapaport et al., 1998), Cannabis sativa (Mandolino et al., 1999) and Actinidia species (Gill et al., 1998). To address the problem of sensitivity, it has been suggested that RAPD marker should be converted to sequence characterized amplified region (SCAR) marker based on their DNA sequence (Paran and Michelmore, 1993). The SCAR marker is sequence-specific and can be used to amplify single bands corresponding to single genetic loci. The conversion of RAPD markers to sex-linked SCAR markers et al., was performed in Salix viminalis (Gunter et al., 2003), in Actinidia chinensis (Gill et al., 1998; Geoffrey et al., 1995) and in Papaya (Urasaki et al., 2002). The aims of this study are to 1identify and discriminate between male and female date palm trees via vegetative virtual external morphological characteristics. 2-identify of male-associated SCAR markers in date palm in order to help for plant grower, in selecting the favorable male plant in their programs in fast cost-effective way.