Regeneration in Cereal Tissue Culture: a Review

This review examines the literature on successful establishment of regenerable cell cultures in the economically important cereal crops. Some of the major trends and strategies for the establishment of in vitro cultures that express totipotency are discussed as well as current approaches. It is apparent that in cereal tissue culture, not all cells express totipotency. Generally the auxin 2,4‐dichlorophenoxyacetic acid (2,4‐D) is critical for the production of regenerable callus; however, the addition of cytokinin can be significant. Meristematic cells from immature tissues are the targets for plant growth regulator action. Some genotypes produce embryogenic cultures, while others are recalcitrant to in vitro manipulation. Regeneration occurs either by somatic embryogenesis or adventitious bud and shoot development with subsequent rooting. In these meristematic tissues, plastids are at the undifferentiated proplastid stage of development. The development of a white, nodulated embryogenic callus in somatic embryogenesis and the formation of green buds during organogenesis suggest divergent modes of plastid differentiation during morphogenesis. Plant growth regulators may be involved with inducing or directing different pathways of plastid differentiation. Genotypic differences in morphogenesis may be due to differences in endogenous hormone levels.