TISSUE CULTURE TECHNIQUES FOR TREE SPECIES

Types of Cultures

Plant tissue cultures can be divided in to five classes based primarily on the type of material used on the medium.

a) Meristem Culture
            This term is often used loosely to refer to very small shoot apices dissected from terminal or lateral buds.  Strictly speaking, it refers to the microscopic apical dome with only the smallest leaf primordial evident, usually less than 2 mm across.  The advantage of using shoot meristem is that they are most likely to be free of internal pathogens.

b) Callus Culture
            Sometimes explants produce callus rather than new shoot growth particularly where high levels of hormones are applied.  In other cases, callus may be induced intentionally because of its potential for mass production of new plantlets.  The limiting factors are the difficulty in inducing the initiation of new shoot apices, especially in woody species.

c.Cell Suspension Culture
            This is essentially product of callus culture, i.e. callus usually refers to a mass of undifferentiated cells.  Once these are separated in liquid culture, it  becomes a cell suspension.  This culture may be used to produce a product directly from these cells without regenerating new plants.  These cells may be genetically engineered to increase the synthesis of different secondary metabolites.