Significance of Protoplast Culture | Biotechnology

In this article we will discuss about the significance of protoplast culture.

Cell Modification by DNA Uptake:

The isolated plant protoplasts are best suited for the introduction of foreign genetic ma­terial. Protoplast acts as an efficient receptor for the uptake of foreign DNA. Protoplast can be regenerated into the whole plant and this is indispensable for genetic manipulation.

The ratio labelled foreign DNA can be detected by autoradiography after introducing into the protoplast. For example, plant protoplasts were fed with ⁴H-labeled E. coli DNA and radioactivity was found in TCA precipitates. This experiment proves that uptake, integration, expression is pos­sible with protoplast system.

Demonstration of Genetic Complementation:

Isolated chloroplasts can be successfully implanted inside the protoplast. The chloroplast has been utilized in several instances of genetic complementation by protoplast fusion. In the fusion process, protoplast containing green plastid fused with protoplast which encloses white deficient mutant plastid resulting in the transformation of white deficient chloroplast into green color after 72 h.

Employing this, it is possible to make complementation between certain chloro­phyll deficient and light sensitive variety.

Protoplast in Studying Nitrogen Fixation:

Plant protoplast is an ideal system for studying nitrogen fixation. Symbiotic nitrogen fixing bacteria Rhizobium can be implanted inside the protoplast and several aspects of higher plant—bacterial symbiosis under in vitro conditions can be studied.

Several in vitro experiments facilitated the establishment of symbiotic nitrogen fixing relationship between plant cell and microorganism. Protoplast acts as a unique single cell system for nitrogen fixation studies.

Underlying this technique, it can be extended for investigating microbial higher plant associa­tion. Modification of protoplast in this way can induce genetic alteration to confer ability of nitrogen fixation on cells of non-leguminous plants.

Uptake of symbiotic Rhizobium or free living non-symbiotic Azotobacter into protoplast may transfer genetic material controlling ni­trogen fixation and even expression of nif genes in free living organisms after fusion of two protoplasts.

Somatic Hybrid Production:

Production of interspecific and intergeneric hybridization through parasexual hybridiza­tion can overcome breeding constraints like incompatibility barrier. Successful cell fusion was accomplished between sexually compatible and incompatible parents which involves intergeneric and interspecific combination.

Protoplast obtained from cultivated rice has been fused success­fully in many wild species of rice. Somatic hybridization often provides unique opportunity for transferring novel set of genes into the solanacean members. Several disease resistant (R) genes have been transferred from potato plant to other species, where crossing is ruled out due to incompatibility barrier.

Similarly, fungal disease tolerance character against Alternaria has been transferred from Sinapsis Alba to Brassica napus. Frost and cold tolerance were intro­duced from Solanum tuberosum to Solanum cammersonii.

Some examples on the introduction of nematode resistance character from Solanum tuberosum into Solanum bulboceraum and S. symbrofoliaum have been established. In addition, certain quality characters like high nico­tine content are passed from Nicotiana rustica to N. tobaccum.

Protoplast Culture in Genetic Engineering:

Protoplast could be used in plant genetic engineering in the transient gene expression studies by consolidating knowledge on promoters, vectors and methods of organelle delivery into the plants. Transformation of monocots, particularly in cereals requires protoplast as an indispensable tool for the introduction of novel genes.

Certain gene introductory methods like electroporation, microinjection are commonly employed in the transfer of novel genes into the protoplast for the production of transgenic plants.