|Wu, Jixiang -|
|Stelly, David -|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2013
Publication Date: N/A
Technical Abstract: Gossypium barbadense (L.), G. tomentosum (Seem.), G. mustelinum (Watt.) and G. darwinii (Watt.) are in the primary gene pool of Upland cotton (G. hirsutum). They share a common chromosome number (2n=52), similar AD-genome architecture, and form reasonably fertile F1 hybrids. However, reduced transmission of much of the alien germplasm during backcrossing, poor performance of most products due to genetic drag effects and genomic incompatibilities at the whole genome level between the species are serious impediments in interspecific introgression using conventional breeding methods. We have developed an unique set of chromosome substitution (CS) lines from G. barbadense (CS-B) and G. tomentosum (CS-T) in a uniform genetic background of G. hirsutum (TM-1) which can help to overcome some of these problems associated with conventional methods of interspecific introgression. Here, we report on chromosome shuffling to determine the chromosomal effects on important agronomic and fiber traits, based on a partial diallel crossing program among six CS-B lines (CS-B01, CS-B04, CS-B07, CS-B08Lo, CS-B15sh and CS-B18), six CS-T lines (CS-T01, CS-T04, CS-T07, CS-T08Lo, CS-T15sh and CS-T18), and the recurrent parent, TM-1. Considering that each substituted chromosome or chromosomal segment introduced potentially significant genetic factors from the donor species in the TM-1 genetic background, the comparative methods were used to detect the chromosome (or chromosome segment) effects on the traits of interest. The parental lines and F2 hybrids from the cross of individual CS line with TM-1 were planted in a randomized complete block design with four replications in five environments. We used an additive-dominance (AD) with G×E interaction genetic model for data analysis. Results revealed that the CS lines harbor useful additive and dominance alleles for specific traits compared to the recurrent parent TM-1. For example, TM-1 had additive genetic effects for fiber strength 0.232g/tex, micronaire 0.020 and lint percentage -0.044, whereas CS-B08Lo had additive genetic effects for fiber strength 1.611g/tex and lint percentage 2.216, respectively. CS-T07 had additive genetic effects on fiber strength 0.703 g/tex and micronaire -0.182, respectively. These findings are significant to germplasm improvement because results revealed that 1) exotic germplasm from unadapted species is a source of new and potentially valuable genes for improving agronomic and other important fiber quality traits; 2) epistasis plays a major role in the observed traits and reveals the cryptic presence of beneficial alleles in genomes of the unadapted species and 3) interspecific chromosome substitution lines can be used as a tool to overcome the biological and technical challenges associated with conventional methods of interspecific introgression and breeding.