CALLUS INDUCTION AND PLANT-REGENERATION FROM EMBRYOS IN BREAD WHEAT (TRITICUM-AESTIVUM L)

Plant regeneration through callus cultures obtained using immature emb ryos in interspecific/intergeneric (Ushiyame et al. 1991, Chen et al. 1992, Girko et al. 1992) and mature embryos in intervarietal crosses ( Girko and Voloshehuk, 1991) has far reaching implication in wheat impr ovement programmes. This is rather pertinent when wheat breeders are c onfronted with gene flow barriers or limitations of time and space. Th e success of plant regeneration through embryo cultures is apparently influenced by culture medium and manipulateable genetic factors which can be controlled and environmental factors which can not be controlle d. Fortunately a strong inherent interaction among these factors exist s which warrants for defining effective embryo culture protocols for a ccelerating the pace of wheat improvement programme aimed at enlargeme nt of genetic variability (Larkin et al. 1984, Bajaj 1986, Ryan and Sc owcroft 1987, Bannikova et al. 1990, Mohmand and Nabors 1990, Sharma e t al. 1992, Oberthur et al. 1993), enhancing gene flow from one geneti c background to the other and development of wheat genotypes tolerant to abiotic and biotic stresses. This review has provided comprehensive information on plant regeneration through embryo culture and warrants a closer interaction between biotechnologists, plant physiologists, g eneticists and wheat breeders.