Submitted to: International Cotton Genome Initiative Workshop
Publication Type: Abstract Only
Publication Acceptance Date: 9/18/2006
Publication Date: 9/18/2006
Citation: Saha, S., Raska, D.A., Jenkins, J.N., McCarty Jr., J.C., Stelly, D.M. 2006. Interspecific chromosome substitution lines in upland cotton improvement. International Cotton Genome Initiative Workshop. p. 11.
Technical Abstract: Despite the economic importance of Upland cotton, the genetic base of US cultivars and elite germplasm is very narrow. Two of the primary impediments to genetic improvement of cotton are: 1) insufficient information about genes that control important traits and 2) under-utilization of diverse germplasm. Wide-cross introgression typically requires considerable time and effort to circumvent and overcome biological, genetic and cytogenetic obstacles, and the choice of breeding strategies to introgress germplasm can greatly influence success. Conventional methods of interspecific introgression into cotton typically entail inbreeding immediately after hybridization or after a few backcrosses. A complementary approach is alien chromosome substitution. The overall goal of this project is to develop chromosome substitution lines from the other tetraploid species into Gossypium hirsutum. Development of each alien species chromosome substitution line involves three stages:  development of the respective TM-1-like hypoaneuploid stock,  use of the cytogenetic stock as recurrent seed parent in a recurrent backcrossing program to create a monosomic or monotelodisomic substitution stock, followed by  inbreeding to recover a euploid disomic substitution line. TM-1, the highly inbred Upland cotton (G. hirsutum) genetic standard, serves as the recurrent parent. The backcrossed chromosome substitution lines are expectedly quasi-isogenic to TM-1 and to each other, except that each line differs by the replacement of a specific homologous pair of chromosomes or chromosome segments from the donor alien species. When possible, the cytogenetic and genetic constitution of the disomic lines is confirmed by cytological analysis and chromosome-specific SSR markers. We released 17 backcrossed (BC5) G. barbadense chromosome or chromosome arm substitution lines (CS-B). These CS-B lines are providing important information about the association of G. barbadense substituted chromosome association with important fiber and agronomic traits. They have also been used to discover their merits in Upland cultivar improvement. For high-resolution analysis of QTLs, we are using many of the CS-B lines in development of chromosome-specific recombinant inbred lines. In addition to the disomic CS-B lines, we also have developed 13 monosomic and 32 monotelodisomic substitution stocks (BC0F1) for different chromosomes or chromosome arms of G. tomentosum and G. mustelinum. Research is also underway to use these for disomic chromosome substitution line development. These new genomic resources will complement the conventional types of interspecific introgression in Upland cotton improvement. All of these materials will provide additional tools in genomic analysis and genetic improvement of Upland cotton.