Genetic Dynamics of Allotetraploid Cotton Species (Gossypium spp.) and Their Utilization in Breeding for Superior Fiber Quality

The restricted genetic diversity of current cotton varieties (Gossypium hirsutum L.) considerably limits breeding opportunities aimed at enhancing fiber quality and resistance to environmental factors. Wild types of allotetraploid cottons are valuable sources of genetic variation, and their breeding potential has not yet been fully utilized. In this study, the inheritance and variability of important agronomic traits were analyzed in F1 and F2 hybrid generations obtained from intra- and interspecific crosses involving G. hirsutum, G. barbadense, and G. darwinii. The phylogenetic relationships of allotetraploid species were analyzed using molecular-genetic and cytogenetic methods, and their breeding potential was evaluated. Cytogenetic analysis of the F1 hybrids revealed the occurrence of univalents at metaphase I of meiosis, while bivalent numbers reached 25.9 in some hybrid combinations. Based on molecular marker analysis, significant genetic differences and polymorphism were identified between var. gambia and var. m. palmerii. There were reciprocal translocations, shown as multivalents, during ecotypic differentiation in other cross combinations. Positive transgressive segregation for the enhancement of fiber length was identified in F2 populations. Notably, in certain hybrid combinations, fiber length extended to 40.9 mm. Furthermore, molecular analysis identified 113 unique alleles across the genotypes examined. These findings affirm that wild and exotic allotetraploid cotton forms constitute a significant source of genetic diversity for breeding programs.

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