Estimation of arsenic-induced genotoxicity in melon (Cucumis melo) by using RAPD-PCR and comet assays

Yonca Surgun-Acar

doi:10.2298/botserb2101097s

Abstract

In this study, arsenic (As)-induced genotoxicity in the roots and shoots of Cucumis melo (melon) seedlings were investigated by using the random amplified polymorphic DNA - polymerase chain reaction (RAPD-PCR) and comet assays. For this purpose, melon seedlings were exposed to arsenate [As(V)] at 0, 100, 200, 300, and 400 ?M concentrations in the hydroponic system for 14 days to examine the level of As accumulation, alterations in growth parameters, and DNA damage. A reduction in growth with increasing As(V) concentration was observed in the melon seedlings. Total As accumulations in the shoot and root tissue increased in a dose-dependent manner; however, the level was higher in the roots than the shoots. In RAPD-PCR analysis, 26 primers gave reproducible and scorable results and produced a total of 128 bands in the control seedlings. Alterations in RAPD profiles, including the loss or appearance of new bands, were determined in the As-treated seedlings when compared to the control. The values of genomic template stability (GTS) were decreased by increasing the concentration of the As(V) in both tissue types. DNA strand breaks were observed in all the tested As(V) concentrations in the alkaline comet assay; furthermore, the loss of DNA integrity was higher with 300 and 400 ?M As(V) treatments. The results clearly indicate that the combination of DNA-based molecular and cytogenetic techniques (e.g. the comet assay) may be proposed as a reliable evaluation of genotoxicity in plants after exposure to heavy metal pollution.

Highlights

Arsenic (As) is a metalloid naturally found in the environment generally in combination with elements such as tin (Sn), silver (Ag), gold (Au) and copper (Cu)
Treatment with As(V) at 100, 200, 300 and 400 μM caused a reduction in shoot length of 11.03%, 39.14%, 56.93%, and 60.67%, respectively, compared to the control samples (Table 2)
Arsenate applications reduced the primary root length in all the tested concentrations, while the maximum decrease was determined subsequent to 400 μM As(V) treatment when compared to the control group (Table 2)

Summary

Introduction

Arsenic (As) is a metalloid naturally found in the environment generally in combination with elements such as tin (Sn), silver (Ag), gold (Au) and copper (Cu). Arsenic can be found both in organic (dimethylarsinic and monomethylarsonic acid) and inorganic forms (arsenate and arsenite) in nature (Tu et al 2003). Inorganic As is categorized as a Group 1 carcinogen (IARC 2004) and people are at risk due to its entry into the food chain (Chakraborti et al 2003). Arsenic accumulation disturbs the prooxidant-antioxidant balance, triggers signal transduction and leads to the generation of reactive oxygen species (ROS) such as superoxide radical (O2−), hydrogen peroxide (H2O2) and hydroxyl radical (OH) in the cell which induces oxidative stress (Leterrier et al 2012). Intensive oxidative stress causes DNA damage, altering its coding sequences and affects cellular processes

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