Earlier (MNL65:88) we reported numerous quantitative and qualitative deviations from the standard pattern in anodal esterases and peroxidases in plants regenerated from tissue cultures of A188 immature embryos. Some loci were affected by somaclonal variation more often and to a greater extent than the others, and the tissue-specific loci seemed to exhibit this variation more readily than the constitutive loci.
Two further generations of these somaclones were obtained by selfing, and their isozyme patterns were surveyed. Several subfamilies (especially 11-4, 27-5 and 54b-7) were found to maintain and gradually intensify some of the previously described somaclonal variations. The most spectacular among them were: (1) the changes in the zone between e4 and e9 esterases: appearance and gradual activation in the leaves of several bands including characteristic "scutellum-specific bands", and the loss from the roots of several bands localized in the same zone of the esterase spectrum; and (2) the emergence of the most mobile anodal peroxidase band (apparently the root-specific product of px12) in the leaves. Several loci manifested considerable heritable changes in the level of their activity as compared to the standard (the initial inbred plants). The most prominent example was px3 activation in the roots of somaclones progressing in their progeny.
In agreement with earlier data, no significant changes were found in cathodal peroxidase spectra.
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