Genetic Engineering and Tissue Culture of Roses

The recent advances in rose genetics and in functional genetics described in the previous two chapters have improved our knowledge about interesting characteristics of the rose. Gene transfer technologies may facilitate the introgression of homologous or heterologous genes to improve major ornamental traits as e.g., scent, plant architecture and color as well as biotic and abiotic stress responses and yield. Genetic transformation of roses requires the availability of reliable protocols for in vitro culture, for the transfer of genes and for selection and regeneration of transgenic plants. As for many other ornamental crops, in vitro culture of roses can be used (i) for rapid multiplication of commercial cultivars, (ii) to produce healthyand diseasefree plants and finally (iii) as a source of explants for plant regeneration as a prerequisite for transformation techniques. In vitro propagation of roses is common practice, particularly for the propagation of pot roses. First reports of in vitro culture of rose (Rosa multiflora) were made by Elliot (1970). The methods of micro propagation of roses in vitro were reviewed several times (Skirvin et al., 1984; Rout et al., 1999; Borissova et al., 2000; Jabbarzadeh and Khosh-Khui, 2005; Pati et al., 2006). An efficient in vitro plant regeneration protocol with high multiplication rates is the ‘key’ technology for various biotechnological techniques such as multiplication of clonal plants, mutation breeding programs by exposing to irradiation or by somaclonal variation, and biolistic or Agrobacterium-mediated transformation. However, the wide range of explants and experimental approaches that have been employed with different rose species and cultivars strongly suggest that a universal, cultivar-independent method for the production of regenerating tissues, coupled with efficient conversion and ex vitro acclimation of regenerants, will be difficult