General Account of Suspension Cultures
The movement of nutrient medium in suspension culture provides vital aeration of the medium to sustain cell respiration in the liquid medium and also encourages the callus tissue to brake up. As the cell division starts in the callus tissue, they shed and dispense directly into medium. A more friable callus tissue is an ideal material for the dispersion of cells. Increasing the concentration of auxin or adding very low concentration of cellulose and pectinase enzymes in the liquid medium are also effective for dispersion of cells.
The period of incubation during which the suspension culture is developed from callus tissue is usually called as initiation passage. In general, media suitable for growing callus cultures for particular species are also suitable for growing suspension cultures provided that agar is omitted. The concentration of auxin and cytokinins used for callus cultures is generally reduced for suspension cultures.
The cells within the aggregates in a different microenvironment from the free floating cells. The cells in suspension may vary in shapes and sizes. They maybe oval, round elongated coiled etc. although suspension cultures consist of thin walled cells, other posses a proportion of lignified, tracheid like elements. These usually arise in the cell aggregates.