BIOTECHNOLGICAL APPROACHES IN 
                   PLANT BREEDING
       Biotechnology is the age-old technology of using biological tools for the 
                                   th
       improvement of  human  life.  The  20   century  witnessed  tremendous 
       advancements  in  different  areas  of  biotechnology  like  microbial 
       technology, genetic engineering and in vitro culture technology. In vitro 
       culture  technology,  molecular  genetics  and  genetic  engineering  have 
       contributed new and unique tools and techniques to plant breeding.
        APPLICATIONS OF IN VITRO CULTURE 
           TECHNOLOGY IN PLANT BREEDING
       •   In vitro culture is the culturing of cells, tissues and organs under aseptic 
           laboratory conditions in culture media. The culture medium generally 
           contains  the  macronutrients  and  other  supplementary  materials  like 
           micronutrients necessary for plant growth and materials like vitamins, 
           amino acids, carbohydrates and growth regulators.
       •   Plant  parts  known  as  explants  are  cultured  in  the  nutrient  medium. 
           Explants  may  be  roots,  cotyledons,  leaves,    shoots  apices,  nodal 
           segments, anthers, embryos etc. The explants are surface sterilized with 
           disinfectants like sodium hypochlorite or mercuric chloride, washed with 
           sterile water and cultured in the nutrient media at 25 ± 10℃.
       •   Usually depending upon the nature of the explant, the nutrient medium 
           and  the  hormonal  combination,  development  of  callus  (an 
           undifferentiated  mass  of  tissue)  or  direct  plantlets  from  the  explant 
           takes place within 3-4 weeks.
          APPLICATIONS OF IN VITRO CULTURE 
            TECHNOLOGY IN PLANT BREEDING
        The callus is subcultured after every 3-4 weeks. The subcultured callus is 
        made to differentiate and produce the shoot system and root system, by 
        altering the composition of the culture medium. Somatic embryogenesis 
        can also be attempted in callus culture. It is the development of embryo-
        like  structures  from  cell  culture.  Such  somatic  embryos  can  be 
        encapsulated  in  a  suitable  matrix  like  sodium  alginate  and  synthetic 
        seeds can be produced. Synthetic seeds can be stored for several years 
        and used as natural seeds. The major applications of  in vitro culture 
        technology    include   micropropagation,   somatic    embryogenesis, 
        exploitation of somaclonal variation, meristem culture, anther culture, 
        pollen culture, embryo culture, protoplast culture, cryopreservation of 
        germplasm, secondary metabolite production and in vitro mutagenesis 
        from plant cell culture.
         MICROPROPAGATION
    This is the bulk production of clonal plants for rapid propagation. It is an 
    important application of tissue culture technology in plant breeding. It is 
    independent of seasonal and regional constraints. The plants produced 
    in  this  way  are  true  to  type,  i.e.,  they  resemble  parent  plants.  Rapid 
    multiplication  of  planting  materials  of  unique  plants  with  disease 
    resistance  and  good  quality  can  be  carried  out  by  this  technique. 
    Uniform behavior of the clonal crop is highly advantageous in terms of 
    agronomic and harvest practices. But the chances of susceptibility to 
    new  strains  of  pathogens  and  adverse  environmental  conditions  are 
    always associated with such genetically uniform crop populations.