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Cotton is an important crop in the textile, food and pharmaceutical industries. In the present study, a panel of 108 elite cotton (Gossypium hirsutum L.) lines was genotyped with 177 genome-wide SSR markers to assess genetic diversity, linkage disequilibrium, population structure and association analyses. A total of 967 loci were assayed and the lines fell into four main groups with a mean genetic distance of 39%. The linkage disequilibrium (LD) decay rate was estimated to be 20-30 cm (r 2 B 0.5). Association analyses were performed with both general linear model and mixed linear model methods to identify SSR marker loci linked to Verticillium wilt resistance. Verticillium wilt is a fungal disease that causes huge yield losses in cotton production throughout the world. A total of 26 marker loci distributed on 14 chromosomes were associated with resistance at p B 0.05. Eight of the 26 associated marker loci were highly significant (p \ 0.01). The phenotypic variation explained (r 2 ) by individual markers ranged from 3.2% to 8.2%. Three of the 26 marker loci (JESPR153, JESPR274 and CIR218) were consistent with previous studies. Our results should be useful in improving Verticillium wilt resistance in cotton breeding lines.

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The concentration and impact of 1,1,1-trichloro-2,2-bis(4-chlorophenyl)-ethane (DDT) and its metabolites (DDE: 1,1-dichloro-2,2-bis(4-chlorophenyl)ethylene) on the environment was expected to decrease after its ban in the mid-1980s. Unfortunately, DDT contamination via its presence as an impurity in dicofol (2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethanol) has led to a new source of contamination. This is particularly true especially in cotton production in Söke Plain, Turkey, where difocol-based pesticides are being used. The aim of this research was to investigate the extent and source of DDT contamination in cotton soils. Söke Plain soil samples were collected from 0-30, 30-60, and 60-90-cm depth and analyzed by GC/MS/MS. o,p'-DDT and p, p'-DDE were detected at 16.2 % and 17.6 % of the sites in the 0-30-cm depth of soils. In the 30-60 cm, p, p'-DDT (14.9 %), o, p'-DDE (8.1 %) and p, p'-DDE (2.7 %) were found in soil samples, and p, p'-DDT was the most prevalent with 9.5 % of the sampling sites. The dominant source of DDT particularly in the 60-90-cm depth was due to historic use of DDT. The presence of p, p'-DDE, o, p'-DDE and p,p'-DDT in the topsoil was attributed to recent dicofol applications.