Crop Improvement Through Plant Tissue Culture - Crop Improvement: New Approaches and Modern Techniques - page 124

Introduction
Plant biotechnology involves a number of technologies and the techniques, methods
and strategies involved in in-vitro culture are only a part of it. Plant tissue culture has
now become a major component of this applied branch. Advances made in molecu-
lar biology can be manifested in plants through plant tissue culture. This technique
is new and has changed the scenario of plant science (Hussain and Hasnain 2012 ).
Apart from the conventional methods of pollination and cross fertilization, there are
a number of methods for producing genetically modified plants. Last 20 years have
witnessed a number of developments in this field. However, the modern molecular
biological techniques are still under way to make a broad based development on
crop improvement to raise a selected plant to the stage of cultivar release (Hussain
et al. 2011 ). A number of recalcitrant crops are now able to regenerate using the
techniques of in-vitro culture utilizing cells or calli or protoplasts in this process
and each such explants can be used in genetic transformation (Davey et al. 2005 ).
Now a days the application of tissue culture to various branches of plant science
like plant breeding, horticulture, forestry, industrial production of compounds and
conservation of ever depleting natural genetic resources has been the focal point of
research (Roy et al. 2011 ).
Advancement in the techniques of protoplast, cell, tissue and organ culture and
regeneration of whole plants has resulted in the development of tissue culture as a
technology (Thorpe 2012 ). The technique has advanced rapidly over the years due
to extensive investigations into problems related to basic and applied aspects of
plants. The phenomenon of growth, metabolism, differentiation and morphogen-
esis can be well understood by the knowledge of tissue culture (Karkonen et al.
2011 ). Plant tissue culture is of great interest to molecular biologists, plant breeders
and industrialists. The methods of tissue culture have been used as an important
aid to conventional methods of plant improvement. They have been used for the
production of genetically modified superior clones, ex-situ conservation of germ-
plasm, pathogen free plants as well as in the synthesis of many important secondary
compounds (including pharmaceuticals). The advantages offered by tissue culture
in agriculture and general plant biotechnology have well been witnessed by many
research labs and industries (Mustafa et al. 2011 ).
The conventional breeding programmes can be complemented by biotechnol-
ogy and expedite the crop improvement programmes. A large number of centres
are involved in studies involving in vitro culture and selection, micropropagation,
embryo rescue, genetic transformation, marker assisted characterization and DNA
fingerprinting worldwide. Micropropagation protocols and somatic embryogenesis
has been achieved in a number of important genera. Germplasm screening has be-
come successful due to the techniques of in vitro selections for antibiotic tolerance
and fungal toxin resistance. Agrobacterium tumefaciens mediated transformation
has been established in a number of cereal, fruit and vegetable crops (Azria and
Bhalla 2011 ; Pons et al. 2012 ). A number of fruit ripening genes have been cloned
and transferred into plants and DNA fingerprinting for genetic diversity analysis