ABSTRACT
Interspecific hybridization has been central to the evolution, domestication, and improvement of Upland cotton, the cultivated form of Gossypium hirsutum. As the world’s most important fiber crop species, Gossypium hirsutum belongs to the allotetraploid Gossypium clade that consists of six additional species. The lint fiber evolved only once in the history of Gossypium, in the ancestor diploid A-genome species, and this trait was passed on to the allopolyploid species when the A-genome united in a common nucleus with a D-genome from the other ancestor that produced no lint fibers. The domestication history of G. hirsutum involved the collection and use of lint fibers by indigenous people for the purpose of making strings and other textile products; hence, spinnable lint fibers were likely to have evolved under domestication. The geographical distribution of G. hirsutum overlaps with G. barbadense and G. mustelinum, and gene flow among these species has been documented. Therefore, the introgression of novel alleles into G. hirsutum possibly contributed to greater ecological adaptation in colonizing new habitats and providing important sources of genetic variation for artificial selection in the early domestication efforts. In modern Upland cotton, numerous germplasm lines have been developed from crossing with G. barbadense. However, reproductive barriers such as reduced fertility, segregation distortion, and hybrid breakdown are often observed in later
Interspecific Hybridization for Upland Cotton Improvement Peng W. Chee1,*, Andrew H. Paterson2, Joshua A. Udall3 and Jonathan F. Wendel4
1 Institute of Plant Breeding, Genetics, and Genomics, University of Georgia – Tifton Campus, Tifton, GA 31794, USA, E-mail: pwchee@uga.edu
2 Plant Genome Mapping Laboratory, University of Georgia, Athens, GA 30602, USA, E-mail: paterson@uga.edu
3 Department of Plant and Wildlife Science, Brigham Young University, Provo, Utah, USA, E-mail: jaudall@byu.edu
4 Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50011, USA, E-mail: jfw@iastate.edu
* Corresponding author
generation hybrids between G. hirsutum and the other polyploid species, complicating the task of introgressing new, stably inherited allelic variation from inter specific hybridization. Recent efforts in molecular genetic research have provided insights into the location and effects of QTLs from wild species that are associated with traits important to cotton production. These and future research efforts will undoubtedly provide the tools that can be utilized by plant breeders to access novel genes from wild and domesticated allotetraploid Gossypium for Upland cotton improvement.
