Mutations by insertional

Mutations by insertional inactivation are responsible for the change of phenotype in other plant pathogenic bacteria. Loss of tumorigenicity has been observed in A. tumefaciens by spontaneous insertion of an IS-element in the T-DNA. It should be recalled that Tn5 insertional inactivation of the T-DNA genes was used to isolate mutants which either were avirulent or caused formation of morphologically altered tumors on tobacco different hosts of Agrobacterium. 

Suppressor of amber (UAG) mutation by inserting Tyr. Strains carry the gene tyrT) for tyrosine tRNAl. Required for lytic growth of S7 or SI00 X phage (e.g., Xgtll)... 

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