Title: Hypoaneuploid chromosome substitution F1 hybrids of Gossypium hirsutum L. x G. mustellinum Miers ex Watt Authors
Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 9, 2013
Publication Date: April 1, 2013
Repository URL: http://handle.nal.usda.gov/10113/56977
Citation: Saha, S., Raska, D.A., Stelly, D.M., Manchali, S., Gutierrez, O.A. 2013. Hypoaneuploid chromosome substitution F1 hybrids of Gossypium hirsutum L. x G. mustelinum Miers ex Watt. Journal of Cotton Science. 17:102-114. Interpretive Summary: The narrow germplasm base of the Upland cotton (Gossypium hirsutum) breeding gene pool is one of the principal constraints in improving cotton production worldwide. The wild tetraploid cotton species are reservoirs of many beneficial genes for pest and disease resistance, and improved agronomic and fiber traits. Gossypium mustellinum Miers ex Watt, native to the semi-arid regions of northeast Brazil, is one of the five allotetraploid species in the primary gene pool of Gossypium. It contains a very high level of heliocides and other allochemicals that contributes to the reduction of certain cotton insect populations. The narrow genetic base in Upland cotton can be improved with interspecific introgression from the wild tetraploid species. Breeders face many challenges in conventional interspecific crosses due to incompatibility at the whole genome level between the two species. A complementary approach to conventional introgression is the development of chromosome substitution lines. Aneuploid plants missing different chromosome or chromosome arms from interspecific crosses are the platform for developing chromosome substitution lines. The challenges in developing such aneuploid plants vary among different crop species and chromosomes. We report for the first time in this paper on the development of 25 such hypoaneuploid hybrids, which include 13 monosomic hybrids, each missing a different G. hirsutum chromosome and 12 "monotelodisomic" hybrids, each missing the distal segment of a chromosome arm. These aneuploid chromosome substitution stocks are useful resources for localization of genomic markers, for development of backcross substitution lines, for integration of molecular maps, and toward high-resolution chromosome-specific genetic dissection of complex traits.
Technical Abstract: Wild tetraploid cotton species are reservoirs of many beneficial genes for pest and disease resistance, and improved agronomic and fiber traits. The lack of alien species genes in elite cotton cultivars suggests that specialized and improved methods of breeding are needed to achieve successful interspecific introgression to improve Upland cotton. Alien gene retention and genetic recombination are often very limited in conventional methods of interspecific introgression in Upland cotton due to genomic incompatibility between the two species. An alternative approach is germplasm introgression through the use of chromosome substitution lines. Interspecific cotton chromosome substitution line development using cytogenetics requires synthesis of interspecific F1 hybrids that lack specific chromosomes or chromosome segments. The difficulty in developing such hypoaneuploids varies widely among crops and chromosomes, but it is feasible in Upland cotton ([AD]1 genome, n = 26), in which existing hypoaneuploid stocks already provide about 75% coverage of the genome. The species G. mustellinum Miers ex Watt, a native to the semi-arid regions of northeastern Brazil, is very distinct from the other tetraploid species in morphology. It contains a very high level of heliocides and other allochemicals that contribute to reduction of certain cotton insect populations. The objective of this paper is to report on the development of the aneuploid F1 chromosome substitution stocks in G. hirsutum for whole chromosomes and chromosome arms of G. mustellinum. Hypoaneuploid plants that lack specific chromosomes or arms were detected by analysis of phenotypic syndromes, conventional meiotic metaphase I configuration analysis of acetocarmine-stained microsporocytes (“pollen mother cells”) as well as the use of deletion analysis with chromosome specific SSR markers. Here, we report for the first time the development of 25 such hypoaneuploid hybrids, which include 13 monosomic hybrids, each missing a different G. hirsutum chromosome (chromosome 1, 2, 4, 6, 7, 9, 10, 12, 16, 17, 18, 20, and 25, respectively), 12 "monotelodisomic" hybrids, each missing the distal segment of a chromosome arm (Telosome for Te05Lo, Te08Lo, Te11Lo, Te11sh, Te12Lo, Te14Lo, Te15Lo, Te20Lo, Te20sh, Te22Lo, Te22sh, Te26sh, respectively). These hypoaneuploid chromosome substitution stocks represent an additional genetic resource for localization of genomic markers, definition of linkage groups, validation of genome maps, and provide a basic foundation towards the development of backcross substitution lines. These lines are therefore useful resources toward targeted germplasm introgression and genetic dissection of complex traits in cotton.