Isozyme studies during differentiation in callus cultures

Plant cell and tissue culture techniques are being increasingly exploited in biochemical studies since they are easy to culture and can be studied under defined conditions. Isozyme analysis at different stages of cultures might throw light on the physiological, biochemical and genetical changes during differentiation.

An attempt was made in the present study to establish a correlation between morphogenic response and isozyme expression, which could be used as a marker system to differentiate the organogenetic potential of callus cultures. Peroxidase, esterase and malate dehydrogenese (MDH) isozyme pattern were studied at four stages, viz. explant, callus, root formation, and shoot formation of cultures, derived from seedling root, immature embryo and immature glume of a local variety of sweet corn (obtained from Maize Research Station, Amberpet, Hyderabad).

In general, during shoot formation all three explant cultures exhibited more peroxidases (PER), esterases (EST) and MDH isozymes than in the callus and root formation stages. Similarity index (SI) was made based on the analysis of isozymes present or absent in the four stages of the three explant cultures (Table 1).

The SI differences for the three enzymes in callus cultures varied from 0.222 to 0.636. The lowest Sl was observed in MDH isozyme patterns for seedling root callus, during the shoot formation stage (greening), whereas the highest (0.636) was observed for the glumes during the shoot regeneration stage. There was a high similarity index for peroxidase and esterase for shoot formation in the shoot forming stage of the seedling root, whereas low levels were observed in the stages of shoot formation of embryo and glume. This variation in similarity index clearly indicates strong differences of isozyme patterns of peroxidase, esterase and MDH during differentiation.

Table 1.

K.V. Rao, P. Suprasanna and G.M. Reddy
 
 


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