Genetic Polymorphism of some Medicinal Plants Belonging to Brassicaceae Using Molecular Markers

Abstract

Exploitation of genetic variability is of major importance in basic genetic studies and in plant improvement programs. The Cruciferae (Brassicaceae) is the largest family of the Brassicales order. It is a natural family of major economic importance. The number of genera about 365 and the number of species about 3250, Mabberley (1997) and Judd et al. (1999) recorded 419 genera and 4130 species belonging to this family and is classified into 13 tribes. In Egypt, Teckholm (1974) recorded 61 genera and 106 species distributed in different habitat types. On the other hand, El-Hadidi and Fayed (1995) recorded 55
genera and 108 species for it.
Mustard plants or their oils can heal rheumatic pains and as emetic in cases of poisoning. It may be used as stimulant for the heart (Naim et al., 1984). Brassica are major oil crop and broccoli, cabbage and mustard are important part of human diet worldwide. In general, genetic improvement of crops can be accelerated when broad genetic diversity and the information of these genetic resources are available. The collection of these genetic resources and the assessment of genetic diversity within and between species should have high priority. Traditionally, markers based on morphological differences among individuals have been used to demonstrate the genetic variability, but with the development of electrophoretic techniques, the biochemical analysis become the cheapest and simplest methods that offer sufficient information to use in plant breeding and serve as a starting point for DNA-based studies (Popov et al., 2002). Moreover, the best molecular markers for genome mapping, marker assisted selection, phylogenetic studied, and crop conservation has low cost and labor requirements and high reliability is called inter simple sequence repeat (ISSR), has been available (Zietkiewicz et al., 1994). Microsatellites are very short (usually 10-20 base pair) stretches of DNA randomly and widely distributed along the genome and they can be analyzed efficiently by the polymerase chain reaction (PCR), using specific primers (forward and reverse) to their flanking regions. The variation in (PCR) product length is a function of the number of SSR units. Primers based on a repeat sequence, such as (CA)n, can be made with a degenerate 3'-anchor, such as (CA) 8 RG or (AGC) 6 TY (Tsumara et al., 1996; Nagaoka et al., 1997). ISSR markers were successfully used for estimating the genetic diversity in several crops, for instance barley (Afiah et al., 2007a) and canola (Afiah et al., 2007b; Afiah and Farag, 2008). In this study isozyme and ISSR were carried out on 11 ecotypes of the Cruciferae collected from different localities of Egypt and to assess the genetic diversity among them.