Meristems have cells which have the capacity to divide, whereas in permanent tissues, the cells have lost the property of division; some cells will have to undergo de-differentiation to produce new plants.

Conventional breeding is often constrained by the availability of limited number of disease resistant gene. New techniques involving :- genetics, molecular biology, tissue culture have resulted in introduction of identification of the desired gene in the nature, its introduction in the cultivated variety, its multiplication by culturing procedures. Its disadvantage being the leakage of introduced gene in the wild or the possible unforeseen ill effects.

1. Pusa Gaurav
2. Jassids
3. Pusa Sawarnim

1. Single cell protein-Microbes like spirulina can be gown easily on materials like waste water from potato processing plants, molasses, animal manure, even sewage in large quantities & serve as food as it is rich in nutrients & specially proteins (microbial components).
2. 250g of microbe Methylophilus methylotrophus can yield 25 tones of proteins.

Biofortified maize and wheat are considered nutritionally improved, because of following reasons:
(i) Maize hybrids have twice the amount of amino acid. lysine and tryptophan as compared to existing maize hybrids
(ii) Atlas 66 has been used as a donor for developing wheat varieties with improved protein content.