Abstract: The isozyme make up of esterases of the seeds from fifteen species and twenty-three cultivar of Gossypium was analyzed by isoelectrofocusing. The experimental results are summarized as follows: 1. Differeces were observed in the number of esterase isozyme bands among the species of different genome groups. The cultivated species, G. hirsutum (AD)1 gave rise to 46 isozyme bands, the most among the species of the genus Gossypium. G. barba- dense (AD)2, G. arboreum (A2) and G. herbaceum (A1) gave rise to 42, 40 and 38 bands, respectively. In wild species, G. australe (C3) had 20 esterase bands, the least in all species of Gossypium. The bands given rise from other wild species ranged from 26 to 40. 2. Each species of every genome groups had its marker bands. The results were in agreement with the traditional classification and provided some biochemical evidence for modern classification of Gossypium. 3. It was clear that all cotton species of different genome groups contain 5 main isozyme bands, viz. PI=3.85, 4.61, 5.48, 5.73 and 5.91 in the zymograms. In other words, these zymograms are common characters of Gossypium. 4. The esterase of 23 cultivers in four cultivated species studied showed that no variation in isozyme patterns existed within one species, except the disease-resistant variety Hea-7124 which differs from other 4 cultivars of G. barbadense.

Key words: Isoelectrofocusing, Esterases isozyme, Seed, Gossypium