Genetic transformation of wheat: progress during the 1990s into the Millennium

Wheat transformation technology has progressed rapidly during the past deca de. initially, procedures developed for protoplast isolation and culture, e lectroporation- and polyethylene glycol (PEG)-induced DNA transfer enabled foreign genes to be introduced into wheat cells. The development of biolist ic (microprojectile) bombardment procedures led to a more efficient approac h for direct gene transfer. More recently, Agrobacterium-mediated gene deli very procedures, initially developed for the transformation of rice, have a lso been used to generate transgenic wheat plants. This review summarises t he considerable: progress in wheat transformation achieved during the last decade. An increase in food production is essential in order to sustain the increas ing world population. This could be achieved by the development of higher y ielding varieties with improved nutritional quality and tolerance to biotic and abiotic stresses. Although conventional breeding will continue to play a major role in increasing crop yield, laboratory-based techniques, such a s genetic transformation to introduce novel genes into crop plants, will be essential in complementing existing breeding technologies. A decade ago, cereals were considered recalcitrant to transformation. Since then, a significant research effort has been focused on cereals because of their agronomic status, leading to improved genetic transformation procedu res (Bommineni and Jauhnr 1997). initially, the genetic transformation of c ereals relied on the introduction of DNA into protoplasts and the subsequen t production of callus from which fertile plants were regenerated. More rec ently, major advances have been accomplished in the regeneration of fertile plants from a range of source tissues, providing an essential foundation f or the generation of transgenic plants. This review summarises procedures, victors and target tissues used for transformation, highlights the limitati ons of current approaches and discusses future trends. The citation of refe rences is limited, where possible, to the most relevant or recent reports.