Insertional mutagenesis
Another approach for functional genomics involving identification and study of new genes is the use of insertion mutagenesis, which may involve one of the following two approaches: (i) transposon mutagenesis and (ii) T-DNA mutagenesis. In both cases, a known DNA sequence is introduced, which may be randomly inserted at many places in the genome. This insertion of a foreign DNA segment transposon or T-DNA) generally leads to loss of function mutatiol1s or 'gene knockouts' and only rarely leads to gain of function mutations. In each case, phenotype will be altered, suggesting the function of the gene involved in insertional mutagenesis. The insertion sequence (transposon or T-DNA) also allows isolation of the concerned gene which can then be studied. This approach has been extensively utilized for identification and isolation of new genes (see Chapter 8 for some details).