Crop Improvement Through Plant Tissue Culture - Crop Improvement: New Approaches and Modern Techniques - page 130

Germplasm Preservation
Conservation of germplasm, under in vitro storage can be done by slow growth
conditions i.e., at low temperature or by fortifying the medium with growth retard-
ing compounds. This is usually done by cryopreservation or by desiccated synthetic
seeds (Silva et al. 2012 ). All such technologies depend on reducing or stopping
growth and metabolic activity. However, the limiting factors are lack of a com-
mon method suitable for all species and genotypes, the expenditure and somaclonal
variations and non-intentional cell-type selection in the preserved material e.g., cell
divisions resulting in aneuploidy at low temperature or non-optimal conditions giv-
ing a particular cell type a selective growth advantage (Hajari et al. 2011 ).
Plant Tissue Culture, a Back Bone to Genetically Modified
(GM) Crops
The expression of heterosis via hybrid vigour could be realized by performing pol-
lination under controlled conditions as this leads to the development of new genera-
tions that performed better in the field than either of the parents and the progeny of
the subsequent generation. Manipulation of the genetic makeup is one of the major
activities in plant breeding, thus, a availability of genetic diversity is the prerequi-
site in plant breeding (Shefferson and Roach 2012 ). And the role of biotechnology
and tissue culture comes into play in this area for creating genetic diversity and ma-
nipulating genetic variability. Although there is still lot of integration required most
of the plant biotechnology and plant breeding programmes, but field trials of trans-
genics have now become much more common. Therefore, the modern technologies
have revolutionized the advancements in the crop improvement programmes and it
has been predicted for more than a decade (Ranganath 2011 ).
Various plant species are being modified genetically, either by vector dependent
e.g., Agrobacterium or vector independent, which includes biolistic, micro-injection
and liposome methods (Tagaki et al. 2011 ; She et al. 2012 ). In majority of the cases,
tissue culture technology has been used to recover the modified cells or tissues. In
fact, plant tissue culture techniques have played a major and important role in the
development of genetic engineering. Plant tissue culture has helped in achieving
many great successes in the field of transgenics. Davis and Reznikov ( 1992 ) have
set milestones in the field of plant biotechnology by using a range of protoplast,
microscope, tissue and organ culture protocols in many crop plants. Development
of efficient transformation methods can enable the possibility of obtaining trans-
genic events that are devoid of marker gene/s upfront. Eggplant, an economically
important vegetable crop does form only a non-significant percentage of agricul-
tural production as it is susceptible to a number of pathogens with bacterial and
fungal wilts being most devastating. A crop improvement approach has been de-
veloped which involves an Agrobacterium mediated transformation from two types