Assessment of the genotoxicity of endosulfan in earthworm and white clover plants using the comet assay.

Endosulfan, as one of the most widely used organochlorine pesticides in the world, has increased the public concern about genotoxicity in soil ecosystems. The comet assay has been widely used in the fields of genetic toxicology and environmental biomonitoring. In the present study we conducted comet assay of endosulfan in earthworm (Eisenia foetida) and white clover (Trifolium repens L.), which are sensitive organisms suitable for acting as a bioindicator for agricultural ecosystems. Earthworms were exposed to endosulfan concentrations of 0.1, 1.0, and 10.0 mg/kg in the soil. White clover roots were immersed in hydroponic pots containing nutrient solutions of different endosulfan concentrations: 0.1, 1.0, and 10.0 mg/L. Tissues from each treatment were collected on the 7th, 14th, 21st, and 28th days of treatment process. Significant effects (p < 0.01) of both concentrations and times of exposure were observed. And endosulfan induced DNA damage in earthworm and white clover nuclei. The comet assay can be used as a reliable tool for early detection of endosulfan.

Assessment of genetic diversity in cultivars of white clover (Trifolium repens L.) detected by SSR polymorphisms.

White clover (Trifolium repens L.) is an important temperate pasture legume that plays a key role as a companion to grass species, such as perennial ryegrass (Lolium perenne L.). Due to the outbreeding nature of white clover, cultivars are highly heterogeneous. Genetic diversity was assessed using 16 elite cultivars from Europe, North and South America, Australia, and New Zealand. Fifteen simple sequence repeat markers that detect single, codominant polymorphic genetic loci were selected for the study. The genetic relationships among individuals were compared using phenetic clustering, and those among cultivars were compared using nonmetric multidimensional scaling. Intrapopula tion variability exceeded interpopulation variability, with substantial overlap among populations and weak interpopula tion differentiation. No obvious or significant differentiation was observed on the basis of morphology or geographic origin of the cultivars. The number of parental genotypes used to derive each cultivar was not a major determinant of genome-wide genetic diversity. The outcomes of this assessment of genetic variation in elite white clover germplasm pools have important implications for the feasibility of molecular marker-based cultivar discrimination, and will be used to assist the design of linkage disequilibrium mapping strategies for marker-trait association.

Soil genotoxicity assessment: a new stategy based on biomolecular tools and plant bioindicators.

The setting up of efficient early warning systems is a challenge to research for preventing environmental alteration and human disease. In this paper, we report the development and the field application of a new biomonitoring methodology for assessing soil genotoxicity. In the first part, the use of amplified fragment length polymorphism and flow cytometry techniques to detect DNA damage induced by soils artificially contaminated with heavy metals as potentially genotoxic compounds is explained. Results show that the combination of the two techniques leads to efficient detection of the sublethal genotoxic effect induced in the plant bioindicator by contaminated soil. By contrast, the classic mortality, root, and shoot growth vegetative endpoints prove inappropriate for assessing soil genotoxicity because, although they cause genotoxic damage, some heavy metals do not affect sentinel plant development negatively. The statistical elaboration of the data obtained led to the development of a statistical predictive model which differentiates four different levels of soil genotoxic pollution and can be used everywhere. The second part deals with the application of the biomonitoring protocol in the genotoxic assessment of two areas surrounding a steelworks in northern Italy and the effectiveness of this methodology. In this particular case, in these areas, the predictive model reveals a pollution level strictly correlated to the heavy metal concentrations revealed by traditional chemical analysis.