BOTANY Higher Secondary Second Year - Textbooks Online

Protoplasmic fusion
Protoplast fusion facilitates mixing of two genomes and could be
exploited in crosses which are not possible by conventional techniques
due to incompatibility. Even though transfer of a single gene from one
plant to another is desirable and protoplast fusion facilitates easy monitoring
of cell genetic changes. Protoplast fusion could be spontaneous during
isolation of protoplast or it can be induced by mechanical, chemical and
physical means.
The isolated protoplasts are kept in isotonic solution (mannitol and
enzyme mixture) to prevent damage. The isolated parent protoplasts are
fused with a fusogenic agent like Polyethylene glycol (PEG). It is followed
by nuclear fusion and results in a somatic hybrid. The somatic hybrids
are allowed to grow in the same culture medium. The fused protoplast
are then induced to regenerate the cell wall by transferring it into a suitable
medium. This is followed by callus formatiom which leads to regeneration
and organization of tissues.
Practical applications of protoplasmic fusion
Due to the existence of incompatibility prevailing between different
species, protoplasmic fusion greatly compensates for interspecific
hybridization. Somatic hybrids between rice and carrot were produced
only through the process of protoplasmic fusion. Somatic hybrids may be
used for gene transfer, transfer of cytoplasm and production of useful
allopolyploids.
4.5. Single cell protein
Microorganisms have been widely used for preparation of a variety
of fermented foods. Eg. cheese, butter, idlis, etc., in addition, some
microorganisms have long been used as human food, eg. the blue green
alga Spirulina, and the fungi commonly known as mushrooms. More
recently, efforts have been made to produce microbial biomass using lowcost
substrates and use as a supplemental food for human consumption or
used as feed for animals. Cells from a variety of micro-organisms, viz.,
bacteria, yeasts, filamentous fungi and algae used as food or feed are
called single cell protein (SCP).
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