ABSTRACT
Callus is a relatively undifferentiated tissue consisting primarily of parenchymatous cells. Callus tissue can serve as an experimental system to investigate and solve a broad range of basic research problems in plant cytology, physiology, morphology, anatomy, biochemistry, pathology, and genetics. This chapter illustrates the technique of obtaining callus from mature tissues of several angiosperm stems and roots and compares callus growth on a standard medium formulation. An important basic concept in plant tissue culture is that tissue from different species will not grow equally on one specific medium. The chapter focuses on an experiment which illustrates this concept by comparing the growth of tobacco stem pith on a medium designed for it with the growth of stem and root tissues of several other plants on the same medium. Another important basic concept in plant tissue culture is that most tissues require a combination of specific nutrients and plant growth regulators (PGRs) to produce the appropriate growth response of the tissues.
