GENETIC ANALYSIS OF PEROXIDASE AND ESTERASE ISOZYMES IN CALLUS INDUCED FROM MATURE EMBRYOUS OF WHEAT (Triticum aestivum L.) GROWN UNDER DIFFERENT LEVELS OF SALINITY

Fifteen wheat ( T. aestivum. L.) populations represented by five parents and their ten F₁’s generations were used to study the molecular polymorphism of peroxidase isozymes and their response to salinity. zymograms of peroxidaseand esterase molecular forms were obtained using the nondissociating P A G E technique.
                Appearance, disappearance and intensity variation of isoperoxidases and isoesterases in embryo callus tissues after saline treatments suggest that either increasing and suppressing transcription or translation of these isozymes are observed after treatments by seawater. This suggests that salinity might stimulate the induction of many elicitors, thereby, affecting the regulation mechanism of the peroxidase and esterase isozymes loci, causing a transitory inhibition of some molecular forms.
                The peroxidase electrophoresis system declared that the salt treatments had a decreasing effect for Giza 164 and Sakha 69 varieties, while the mutant lines I.A. 51 and I.A.76 were adopted with the salinity stress. The cross between Sakha 8 x I.A. 51 gave the greatest number and high intensity of bands, while Sakha 8 x Sakha 69 had the least number and lowest intensity of bands. The presence of peroxidase molecular forms at 3.2 and 3.5 cm in most crosses in spite of their absence in their parent under saline treatments, clearly suggest that these bands could be considered as salt shock protein bands which appeared after saline treatment, thereby the peroxidase isozyme pattern could be used as a good marker to distinguish the plant tolerant and/or resistance to salinity.
                The zymograms of isoesterase showed that, the lines I.A.51 and I.A.76 were distinguished with stability against the environmental salinity, while the variety Sakha 69 had the lowest number of esterase bands with low intensity. Meanwhile, the cross I. A. 51 x I. A. 76 was the best hybrid, which had the greatest number of bands. Also the electrophoretic profile of esterase isozyme under non-saline conditions revealed that the general variation between the control and salt treatments represented in the four bands at positions 0.3, 0.5, 5.6 and 5.8 cm which were appeared only under all the salt treatments. These results clearly suggested the presence of an association between salt tolerance and the presence of these bands. In addition the esterase isozyme system was a reliable system for discriminating parents and their hybrids under saline condition.