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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.

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.

The Arbuscular mycorrhizal fungi (AMF) are microorganisms that live symbiotically with plant roots and have many benefits to soil and plants. In this study, some effects of AMF which are known to be soil and plant beneficial, have been evaluated and solution proposals have been put forward against heavy metal and salinity stress in the soil. Salt accumulation and high concentrations of heavy metal in the soil affects negatively the microbial diversity and activity. Removal of salt acumulation and heavy metal from contaminated soil by chemical and physical methods is both very expensive and ineffective. Therefore, AMF are important for alleviating the heavy metal and salt stress in plants. AMF can alter plant physiol¬ogy and root morphology, increase the uptake of nutrients and water from the soil through an extensive hyphal network, decrease the use of chemical fertilizer, interact with other soil microorganisms plant growth promoting, induce of some resistance parameters in the plants and produce the glomalin which develops the properties and structure of soil. AMF are eco-friendly solutions according to traditional methods and the use of suitable plant-fungi combinations increases the chances of success of these applications.

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