Saintpaulia (family Gesneriaceae), commonly known as African Violet, is a popular houseplant as a result of its compact size, tolerance of shaded conditions, ease of vegetative propagation, and potential to flower year round. To date ≈20,000 varieties have been produced globally by conventional hybridization techniques and spontaneous mutation, and annually, several hundred new cultivars are released (Ghisleni and Martinetti, 1995). The breeding of Sainpaulia is nevertheless hampered by the low number of wild species available for crosses and the low spontaneous mutation frequencies. For commercial floriculture, development of new and improved varieties is important because it will keep up the interest of the consumers. Today, biotechnological approaches (e.g., mutation breeding, genetic transformation) have proved to be a powerful tool to complement the traditional breeding works in many ornamental species.
Mutation breeding has become increasingly popular in recent times as an effective tool for crop improvement, and more than 2250 mutant cultivars have been released worldwide (Ahloowalia et al., 2004). Artificial mutation induction can be carried out using physical and chemical mutagens and mutation induction with radiation was the most frequently used method to develop direct mutant varieties (Ahloowalia et al., 2004). Several reports on the induced mutation of Saintpaulia using physical mutagens such as ion beam, x-ray, and gamma ray were published in the past (Leenhoots et al., 1982; Wongpiyasatid et al., 2007; Zhou et al., 2006). In these works, although variants were observed in the regenerated shoot population, the procedure required expensive units to operate, which is out of scope for most research and commercial laboratories. Chemical mutagens could be successfully applied to induce mutations where no irradiation facility is available. In some cases, the efficiency of chemical mutagens has proved to be greater than those of physical mutagens (Jacobs, 2005; Rego and Faria, 2001). Among the chemical mutagens, EMS is considered very effective and its effectiveness has largely been demonstrated in cereal crops such as rice (Bhan and Kaul, 2003), wheat (Bozzini and Mugnozza, 2003), and barley (Nicoloff, 2003) as well as in Arabidopsis thaliana (Jacobs, 2005). Recently, this mutagen has also been used to treat seeds and in vitro propagules of many species (Basu et al., 2008; Latado et al., 2004; Luan et al., 2007). To our knowledge, there is no report so far on the EMS use in Saintpaulia; it is therefore our objective to study the possibility of using this mutagen to induce mutations in in vitro-grown Saintpaulia.
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