Somaclonal variation in a maize inbred line is not associated with changes in the number or location of Ac-homologous sequences.

Somaclonal variation (tissue culture-induced mutations) may result, in some instances, from the activation of transposable elements. This study was conducted to determine whether somaclonal variants in the Zea maize L. inbred line FR27rhm were associated with movement of the transposable element Activator (Ac). Ten variants, seven of which from genetic analyses fit a single recessive gene model and three which did not due to a low number of mutant plants, were selected for analysis. Total DNA from these and from uncultured FR27rhm seedlings were examined by Southern blot analysis using the internal 1.6-kb Hind III fragment derived from the cloned Ac7 element as a probe. By using a restriction endonuclease which does not cut within the element, the number and distribution of the copies of Acrelated sequences in the FR27rhm genome could be determined. From the number of bands seen in the blots, we conclude that the FR27rhm inbred contains large numbers of Ac -related sequences. However, the pattern of bands seen in the ten variants and in the uncultured seedlings were identical, indicating that there had been no movement of any of the Acrelated sequences to cause the tissue culture-induced mutations.