Malate dehydrogenase (MDH; EC 1.1.1.37) isozymes in tissues and callus cultures of Cereus peruvianus (Cactaceae).

Malate dehydrogenase (MDH; EC 1.1.1.37) isozymes were investigated in seeds and in seedlings and calli cultures of C. peruvianus to determine if the changes in MDH isozyme banding patterns could be used as biochemical markers to identify the origin of regenerated plants from callus tissues. Four cytoplasmic MDH isozymes (sMDH), five mitochondrial MDH isozymes (mMDH), and one glyoxysomal MDH isozyme (gMDH) were detected and showed tissue- and stage-specific expression. A relationship of mMDH and gMDH isozyme patterns with callus tissues subcultured in three hormonal combinations and with the plants regenerated from these callus tissues was demonstrated. Furthermore, temperature and mechanical stress were found to be closely related to mMDH-1 activity in callus culture. Therefore, the different patterns of MDH isozymes in the various tissues of C. peruvianus can be used as biochemical markers for the study of gene expression during development and as powerful tools in monitoring studies on callus cultures.