A Genetic Map Constructed from an Intraspecific Cross Between a Semi-Wild Line and a Cultivar in Upland Cotton *For Correspondence
RRJBS| Plant Biotechnology and its Applications-S3
INTRODUTION Cotton (Gossypium spp.) is the world's leading natural fiber crop, which supplies approximately 35% of the total fiber used, and cotton also acts as an important oil and protein crop [1-3]. The genus Gossypium identified includes 53 species of two polyploidy levels, of which 47 are diploid (2n=2x=26) and six are tetraploid (2n=4x=52) . Moreover, there are four cultivated species: two diploids, G. herbaceum and G. arboreum, and two allotetraploids, G. hirsutum and G. barbadense.
... nd G. barbadense. Among these species, upland cotton (G. hirsutum) accounts for over 95% of the world cotton production because of its wider adaptability across the globe. However, the narrow genetic background of cultivated upland cotton has resulted in inbreeding depression and reduced genetic variability. Moreover, different degrees of sterility and distinct segregation distortions, and propensity to preserve the parental haplotypes of interspecific hybrids are unusual features which hinder the progress of enriching the genomes of cultivated cotton species [5,6]. For the cultivated species of upland cotton, there are seven races (also named semi-wild cotton) from which the modern cultivated cotton (lines, cultivars or varieties) were directly domesticated, and hence they have the closest relationship. The races have a large indigenous range, collectively encompass a wealth of morphological forms, and span the wild-to-domesticated continuum [7,8] , alleviating the limitation between interspecies and broadening the existing narrow genetic base. Upland cotton (G. hirsutum) is widely distributed in Central and South America, the Caribbean, and even reaches distant islands in the Pacific (Solomon Islands, Marquesas). Hutchinson classified the diversity of upland cotton (G. hirsutum) into ABSTRACT Upland cotton (Gossypium hirsutum) accounts for more than 95% of the world cotton production but its genetic base has seriously narrowed. It is necessary to utilize desirable genes from its semi-wild lines which have enviable traits such as saline-alkaline tolerance. In this study, linkage groups were constructed using an F 2 population derived from an intraspecific cross between a semi-wild line (marie-galante 85) and a cultivar (CCRI-16) in the upland cotton (G. hirsutum L.). The map was based entirely on genome-wide simple sequence repeat markers. A total of 69 loci were mapped in 13 linkage groups covering a genome length of 615 cM with an average inter-locus distance of 8.9 cM. The average length of linkage group in this map is 47.3 cM, with an average number of five loci per linkage group. Based on the common primer SWU11887, one linkage group corresponded to chromosome 2. The results may lay a foundation for quantitative trait loci mapping which will facilitate the improvement of cultivars or varieties within upland cotton.