Instant Notes: Plant Biology

Section O – Plant genetic engineering and biotechnology

O2 Plant cell and tissue culture

Plant cell and tissue culture has been undertaken in various forms since the

1930s, although the techniques derive from the much older techniques of plant

propagation, such as taking cuttings, which have been carried out by

horticulturists for centuries. The techniques are based on the fact that plants

showplasticity of development, the ability to change developmental path if

suitably triggered. Thus, a stem section can regenerate roots and leaves to

achieve a complete, functional plant and single cells can be caused to form an

entire new embryo. Plant tissue culture requires sterile conditions as tissue

growth is slow and material in culture vulnerable to fungal and bacterial infec-

tion. The major types of sterile plant culture are:

Types of cell and
tissue culture

Key Notes

The major types of cell and tissue culture are: organ culture, embryo

culture, tissue culture (production of callus and subsequent regeneration

of organs or plantlets from excised pieces of tissue) and suspension

culture (single cells or cell clumps in liquid media).

Plant cell and tissue cultures must be initiated and maintained in a sterile

environment. Growth media include a carbon source (sucrose), macro

and micronutrients, auxin and cytokinin, vitamins, water and, for solid

media, a solidifying agent like agar.

Suspension cultures are started by breaking callus into liquid medium in

conical flasks, which are agitated in an orbital incubator. Cells show

logarithmic growth initially, then cell division ceases and growth rate

declines. Subculturing to new medium is then required. Suspension

cultures maintained for long periods may alter in properties due to

mutation and altered gene expression.

Differentiation to form roots, shoots and plantlets can be induced by

selecting an appropriate auxin:cytokinin ratio for the medium.

Suspension culture cells will also form embryoids (somatic embryos) in

appropriate conditions.

The major applications of plant cell and tissue culture are

micropropagation, the production of high value products by cell cultures

and as part of the genetic manipulation of plants.

Related topics Biochemistry of growth regulation Molecular action of hormones and

(F2) intracellular messengers (F3)

Plant genetic engineering (O3)

Types of cell and

tissue culture

Methods, media and

equipment

Suspension cultures

Differentiation and

embryogenesis

Commercial and

industrial

applications