. Determine the Callus and suspension culture. Explain
1. Callus And Suspension Culture:
Depending upon the type of explant, tissue culture is called shoot tip culture, multiple shoot culture, anther/ haploid culture, embryo culture, embryoid culture etc.
On the basis of in vitro growth, plant tissue culture are of two types, callus and suspension cultures.
Callus is irregular, unorganised and undifferentiated mass of actively dividing cells. Darkness and solid medium gelled by agar, stimulates callus formation. Both the growth regulators (2, 4-D and BAP) are added. This stimulates cell division in explant. Callus is obtained within 2-3 weeks.
In suspension culture single cells or small groups of cells are suspended in constantly agitated (100-250 rpm) liquid medium having 2, 4-D. In suspension culture growth is faster as compared to callus culture. Agitation helps in aeration of culture, mixing of medium and breaking of cell aggregates into single or few celled, groups. With the passage of time
a. cell/tissue biomass increases,
b. level of nutrients and growth regulators fall,
c. volume of medium declines and there is accumulation and wastes.
Cultures are regularly divided and transferred to containers having fresh media. The process is called subculturing. Callus and suspension cultures are used for increasing cell biomass for biochemical extractions, quick vegetative propagation (through regeneration of plantlets), induction of mutations, development of transgenic plant and isolation of protoplasts.