Abstract:
Mutation breeding has been recognized since the beginning of this century as one of the driving force of evolution, besides selection and evolution. Though mutations are generally recessive in nature and are lethal to the organism, in some cases sudden changes in DNA due to mutagenesis can be harmless. Reversion of a fixed mutation can be eventually possible depending on the presence or the absence of the original DNA. Environmental stress due application of mutagens or tissue culture conditions may activate the transposons which should be the reason of acquired genetic diversity. Development of morphological mutants due to methylation on the restriction sites (epigenetic mutation) may play a more significant role in the evolution. However, these epigenetic mutations have proved to be less stable than normal DNA sequence alterations. Hence conventional methods of mutation breeding remain much acceptable means of crop improvement. Visible macromutants in mungbean are generally the variation in the morphological parameters. The higher doses of physical and chemical mutagenic irradiation in mungbean will provide enough scope to develop a wide range of morphological variation in desirable plant attributes such as multifoliation, variation in leaf lamina, sterility etc. Observation of visible macro mutants such as synchronously maturing and large seeded multifoliate may be progressed in the M2 and M3 generation through directed selection and these stable mutants can be used as donar for restructuring mungbean genotypes. Further analysis of the visible macro mutants can be followed through the use of suitable molecular marker systems such as Restriction Fragment Length Polymorphism (RFLP), Random Amplified Polymorphic DNA (RAPD), Amplified Fragment Length Polymorphism (AFLP) and Simple Sequence Repeat (SSR) and Single Nucleotide Polymorphisms (SNPs). High-density mapping and its application in map-based cloning can be useful technique for isolation of useful genes liked with morphological attributes.
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