Caracterização isoenzimática de clones e somaclones de cana-de-açúcar

Extracts from leaves and roots of three sugarcane varieties and their somaclones: NA56-79 (at seven and nine month old plants), IAC68-12 and IAC68-144 (both at nine month old plants) were obtained. The peroxidase and esterase isoenzyme contents of the extracts were determined to verify the genetic variability of tissue culture somaclones. The peroxidase specific activity was studied in relation to the time and isoenzymatic pattern. The peroxidase and esterase zymograms showed distinct differences among varieties, and the esterase presented less bands but easier to characterize than the peroxidase bands. The root zymograms exhibited great enzymatic variation due to the presence of old roots thus not allowing to characterize the varieties. No differences in peroxidase or esterase zymograms among somaclones of the same variety were noticed. The NA56-79 presented lower specific activity of peroxidase and number of isoenzymes than IAC68-144, suggesting that the decrease of isoenzyme bands is associated to the reduction of enzymatic activity. The specific activity of peroxidase changed with maturity and was higher at nine than at seven month old plants.