Abstract
Nine varieties of American Upland and American-Egyptian cotton, viz. Th41, UKA. B1-(72)049, Bulgaria 996, Coker 100 WILT, Acala 4-42 WR, Deltapine 16, Gregg 35 x L, Pima 55 and Sea Island Seaberry, from different geographic areas, were tested for their genetic variation through polyacrylamide gel electrophoresis of their seed proteins. Considerable variation in their protein banding patterns were observed.
INTRODUCTION
Polyacrylamide gel electrophoresis of seed proteins offers a biochemical approach to understand the evolutionary aspects of plant species. The background and theory, of polyacrylamide gel electrophoresis were thoroughly discussed by Ornstein (1964), and the method and application of the tech-nique to analyse and compare human serum protein were presented by Davis (1964). Amino acid changes within a protein, due to mutational changes, can result in altered protein migration rates when the proteins are compared in the matrix system of poly-acrylamide. Therefore, since species differ genetically at many loci, the individuality of each plant species can usually be expressed according to its protein banding pattern. Steward et at. (1965), Boulter et al. (1966) and Sastry and Virupaksha (1967) modified the polyacrylamide gel electrophorctic tech-nique so as to detect protein changes in de-veloping and in differentiating seedlings and to examine protein content of seeds. The electrophoretic work of many re-Searchers elucidated or confirmed taxo-nomic relations between species obtained previously by well known classical methods. Vaughan et at. (1966) with brassica and
Johnson and Hall (1965) and Johnson et al. (1.967) with Tritioun, were able to confirm relationships of species as well as genomes. Larson (1 967) applied this technique to sep-arate 61 soybean varieties into two main groups on the basis of their seed protein content. Cherry et al. (1969) performed polyacrylamide gel electrophoresis on seed proteins of 26 species and 10 varieties of the genus Gossypiwn and compared the protein banding patterns within and between the six genomes, A, B, C, D, E and •F and of differ-ent allotetraploid forms. In this paper, efforts are made to de-termine genetic variability as measured by protein handing patterns through elee-trophoretic analysis of seed protein of 9 American upland and American-Egyptian cotton varieties of different geographic ar-eas.
MATERIALS AND METHODS
The study was conducted at the Southern Crops Research Laboratory, Crop Germplasm Research Unit, College Station, Texas, USA during February, 1989. Nine varieties of American Upland and American-Egyptian cotton (Table 1) were analysed for their seed protein banding pat-
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