|Wu, Jixiang - MISSISSIPPI STATE UNIV|
|Stelly, David - TEXAS A&M UNIVERSITY|
Submitted to: Journal of Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 11, 2010
Publication Date: March 1, 2010
Citation: Saha, S., Wu, J., Jenkins, J.N., McCarty Jr., J.C., Hayes, R.W., Stelly, D. 2010. Genetic Dissection of Chromosome Substitution Lines of Cotton to Discover Novel Gossypium barbadense L. Alleles for Improvement of Agronomic Traits. Journal of Theoretical and Applied Genetics. 120:1193-1205. Interpretive Summary: Efforts to combine the best features of high-yielding Upland cultivars of Gossypium hirsutum and the superior fiber characteristics of G. barbadense have generally fallen well short of desired goals. Wide-cross introgression typically requires considerable time and effort to overcome biological, genetic, and cytogenetic obstacles. A complementary approach is to use alien chromosome substitution lines. Recently we have released 17 backcrossed (BC5) G. barbadense chromosome or chromosome arm substitution lines (CS-B). The CS-B 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 (3-79) alien species. In this research, we conducted a partial diallel among six selected CS-B lines and the inbred ‘TM-1’, and characterized their lint percentages, boll weights, seedcotton yields and lint yields across four environments. By using the additive-dominance model we partitioned genetic effects for each of the substituted chromosome or chromosome arm into additive, dominance, additive and additive interaction effects. The homozygous dominance genetic effects on seedcotton and lint yield of CS-B22Lo were nearly four times those of TM-1. The results indicate that the substituted chromosomes and arms of 3-79 carried some beneficial alleles with potential to improve agronomic traits including yield, whose effects could not be detected in 3-79. This research helps to overcome two of the primary impediments to genetic improvement of cotton: 1) insufficient information about genes that control important traits and 2) under-utilization of diverse germplasm.
Technical Abstract: Efforts to combine the best features of high-yielding Upland cultivars of Gossypium hirsutum (2n=52) with the superior fiber characteristics of G. barbadense (2n=52) have generally fallen well short of desired goals. In this study, we have used hypoaneuploid-based chromosome substitution as a means for systematically introgressing G. barbadense doubled-haploid line ‘3-79’ germplasm into a common Upland genetic background, inbred ‘TM-1’, and used the resulting ‘CS-B’ lines per se and, their F1s, F2s, and F3 progenies to detect major agronomic trait loci in both G. barbadense and G. hirsutum. To better understand epistatic effects on cotton interspecific breeding and improve wide-cross cotton breeding efficacy, we conducted a partial diallel among six quasi-isogenic CS-B lines and the inbred ‘TM-1’, and characterized their lint percentages, boll weights, seedcotton yields and lint yields across four environments. Data were interpreted according to the ADAA genetic model, which revealed highly significant additive, dominance, and additive by additive epistasis effects on the four agronomic traits associated with the respective substituted chromosome or chromosome arm of CS-B lines. Additive effects for lint percentage were higher for CS-B16, CS-B22sh and CS-B22Lo than TM-1. The homozygous dominance genetic effects on seedcotton and lint yield of CS-B22Lo were nearly four times those of TM-1. Hybrids between CS-B22Lo and TM-1 had the highest additive x additive epistatic effects on seedcotton and lint yield. Our results revealed that multiple antagonistic genetic effects for the agronomic traits associated with most of the substituted chromosomes and chromosome arms, a finding not discordant with their recalcitrance to conventional breeding efforts. The results indicate that the substituted chromosomes and arms of 3-79 carried some cryptic beneficial alleles with potential to improve agronomic traits including yield, whose effects could not be detected in 3-79. It will be useful in future research to test the genetic effects of these beneficial alleles in crosses with improved Upland cultivars.