PJB-1999-2
ISOZYME MARKERS IN COTTON BREEDING 1. STANDARDIZATION OF DIFFERENT ISOZYME SYSTEMS FOR IDENTIFICATION OF DIFFERENT CULTIVARS OF COTTON (GOSSYPIUM HIRSUTUM)
SHAFQAT FAROOQ, NAYYER IQBAL AND ANJUMAN ARA ZAIDI
Abstract
Isozyme peroxidase (Pox), shikimic dehydrogenase (Sdh), superoxide-dismutase (Sod), esterase (Est), phosphoglucoisomerase (Pgi) and catalase (Cat) were standardised for different varieties of cotton (Gossypium hirsutum) and one variety of G. arboreum using stacking and resolving polyacrlyamide gel electrophoresis (PAGE). Isozymes were extracted in different buffers using fresh leaves collected from different cotton cultivars growing in the field. Isozyme shikimate dehydrogenase and esterase have been smdied in different varieties of G. hirsutum in addition to the remaining isozymes which have been reported only for G. arboreum and G. herbaceum. The objectives of the study were to standardize different isozyme systems for G. hirsutum varieties using material collected from field. identification of an isozyme system through which inter and intravarietal differences and genetic changes occurring in the plant growing under stress condition can be detected, and detection of a polymorphic locus which can be correlated with the stress prevailing in the area (s) of cotton cultivation. Electrophoretic profiles of isozymes showed generally monomorphic patterns for isozymes esterase and superoxide dismutase and thus detected minor inter and/or intravarietal differences. The remaining isozyme systems appeared polymorphic and differentiated different plants of a variyty and different varieties from each other. Most of the isozymes appeared to be controlled by one or two loci except peroxidase for which 7 different loci were identified. Possibilities of using the observed isozyme polymorphism in persuing the prescribed objectives are discussed.
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