Mutagenic effects of environmental industrial chemical agents in inducing cytogenetical changes in wheat.

摘要

Six environmental industrial chemical agents, belonging to three separate groups viz. aziridines (metepa, 0.4 and 0.2%) and thiotepa (0.2 and 0.01%); nitroso compounds (N-methyl-N-nitro-N-nitrosoguanidine, 0.1 and 0.05%); and alkane sulphonic esters(methyl methane sulphonate [methyl methanesulfonate], 0.1 and 0.05%) and ethyl methane sulphonate [ethyl methane sulfonate] (0.5%) and used in textiles, drug manufacture and as chemosterilants, were compared for their mutagenicity and related cytogenetical effects on two wheat varieties -- a tetraploid, durum wheat [Triticum durum] var. HD 4502 and a hexaploid bread wheat var. NP 880. Reduction in germination; survival; and root and shoot length under the chemical treatments were observed in both varieties, the tetraploid var. HD 4502 showing more sensitivity than the hexaploid var. NP 880. Among the chemicals, thiotepa, followed by N-methyl-N-nitro-N-nitrosoguanidine, showed drastic reduction in all characters studied in the M1 generation. They alsoshowed drastic effects in terms of cytological parameters (e.g. cell division and chromosomal aberrations). The high mutagenic effectiveness of thiotepa was also indicated by the absence of any dividing cell in the sensitive var. HD 4502, and very high frequency of abnormal cells, clumping and chromosome breakage in the hexaploid var. NP 880. Higher frequency and wider spectrum of viable mutations were also observed in HD 4502. On the overall basis (varieties pooled over mutagens), the highest number ofabnormal cells and shattering of chromosomes were observed under metepa, followed by thiotepa. The other two chemical agents, N-methyl-N-nitroso-N-nitrosoguanidine and methyl methane sulphonate, also exhibited larger chromosomal abnormalities than ethylmethane sulphonate and controls. Thus, the present study clearly demonstrate that environmental chemicals are much more potent mutagenic agents, which could also prove to be hazardous to human health due to their genotoxic and carcinogenic properties.