ASSESSMENT OF LEAD STRESS USING GENOME TEMPLATE STABILITY IN Hordeum vulgare

Abstract

Assement of genotoxins-induced DNA damage at molecular level is important in eco-genotoxicology. In this research, ISSR and SRAP were used to detect DNA damage in barley (Hordeum vulgare L.) seeding exposed to toxic ascending Pb at concentration of 50,100, and 150 mg/l for 15 days. Substantial inhibition of root growth was observed with an increase in the Pb concentration, whereas shoot growth was non significantly inhibited compared to the unexposed plantlets. The alternations in the SDS-PAGE of seed proteins are indicative of the ability of lead (Pb) to alter the gene expression in exposed plant. For the ISSR analyses, 9 ISSR primers were found to produce a total of 53 amplification products (loci) from the nine primers were identified in the control seedlings ranging from 410-1927 bp in molecular size (primer ISSR-9 and primer ISSR-8 respectively). The detected % of polymorphisms was 32.08%, 33.96% and 71.70% for 50, 100 and 150 mg/l lead treatment, respectively. While for the SRAP analyses, three ISSR primers were found to produce a total of 17 amplification products (loci) from the three combinations primers were identified in the control seedlings ranging from 127-1883 bp in molecular size. Different polymorphic bands were detected at each concentration of lead for different primers. The detected % of polymorphisms 52.94%, 58.82% and 70.59% for 50, 100 and 150 mg/l lead treatment, respectively. The number of disappearing SRAP bands was the highest (7) in Pb treated seedlings 150 mg/l. Moreover, the number of appearing SRAP bands was the highest (4) in Pb treated seedlings 100 and 50 mg/l. Results produced from SDS-PAGE, ISSR and SRAP analysis indicated that the evident changes of exposed barley seedlings included gain or loss of bands compared with the control seedlings. The polymorphisms detected by both of SDS-PAGE, ISSR and SRAP profiles can be applied as a tool in risk assessment of Pb stress on plants. The results suggested that genomic template stability (GTS) reflecting changes in SDS-PAGE, ISSR and SRAP profiles was the most sensitive endpoint compared with the traditional indices such as root and shoot growth.