DETECTION OF SOMACLONAL VARIATIONS IN POTATO USING RAPD MARKERS

Abstract

Potato (Solanum tuberosum L.) is an economically important vegetable crop in Egypt. It is the fourth most important crop by volume of production; it is high yielding, having a high nutritive value and gives high returns to farmers. Moreover, potato is considered a good source of antioxidants (Chen et al., 2007). It is vegetatively propagated, heterozygous and tetraploid, thus, traditional breeding of potato is very difficult (Solmon-Blackburn and Baker, 2001). Biotechnology could be contributed to solve this problem and realize great benefit to potato farmers. The regeneration of plants from cell and tissue culture represent an essential component of biotechnology and have the potential not only to improve the existing cultivars, but also for the generation of novel plants in a comparatively short time compared to conventional breeding. The success of plant biotechnology relies on several factors which include an efficient tissue culture system for regeneration of plants from cultured cells and tissues. During tissue culture, changes of interest to plant breeders may be heritable and result from changes in the plastid or nuclear genome. The introduction of variation may also be either problematic or useful for horticulturists and plant breeders and may occur in high frequency during adventitious plant regeneration or long-term callus culture (Kaeppler et al., 2000). Many researchers studied how to standardize the optimum concentrations of growth regulators for regeneration of potato and consequently great progress has been made in potato callus induction and plant regeneration (Ahloowalia, 1982; Dobranszki et al., 1999; Hansen et al., 1999; Ehsanpour and Jones, 2000; Fiegert et al., 2000; Yasmin et al., 2003; Shirin et al., 2007; Khadiga et al., 2009; Khalafalla et al., 2010; Shahabud-din et al., 2011).
DNA markers provided valuable tools in various analyses ranging from phylogenetic to the positional cloning of genes. Scoring of changes morphological and biochemical in plant can be useful in some studies, but there is limited diversity and trait may be affected by environmental influences. Molecular techniques such as Random Amplified Polymorphic DNA (RAPD) is often favored over traditional phenotypic, cytological and biochemical analysis, and generally assess even small variations in the genome. Detection of somaclonal variations using RAPD markers has several advantages, since RAPD markers are technically simple, quick to perform with small amount of DNA and do not require previous information about genome or radioactive labeling (Michelmore et al., 1991). RAPDs are usually dominant and are inherited in a simple Mendelian fashion. Thus RAPD analysis is a useful tool in determining genetic relationships among regenerated potato and their original cultivars. The use of the PCR-based RAPD technique to detect somaclonal variations has been applied successfully to several plant species, such as Lolium (Wang et al., 1993), Allium sativum L (Al-Zahim et al., 1999) and Picea abies (Heinze and Schmidt, 1995). It has also been applied for tomato (Soniya et al., 2001) and potato (Khatab, 2000). The objectives of this study was to investigate the efficiency of callus induction and plant regeneration media for four potato cultivars and also to detect the somaclonal variations appeared after plant regeneration using RAPD markers.