Abstract
The effect of different doses of gamma irradiation on cytogenetic and biochemical characters was studied in two Egyptian cultivars of garlic (Balady and Sids-40). Identification of DNA polymorphism among the treatments through a Randomly Amplified Polymorphic DNA (RAPD) marker analysis was also of interest in this study. The cytological analyses showed that the highest percentage value of mitotic index (MI) was recorded for cultivar Sids-40 (13.07 ± 2.04) at 1000 rad, while the dose 1250 rad exhibited the lowest value (4.65 ± 0.43) for Balady cultivar. It was of specific interest to notice that the γ-irradiation dose of 4000 rad which caused the significant decrease in MI in Sids-40 garlic cultivar gave also the highest values of chromosomal abnormalities in the same cultivar. Both the lowest and highest γ-irradiation doses used (500 and 8000 rad, respectively) caused increase in MI in both garlic cultivars. While, the 4000 rad dose caused decrease in both garlic varieties. On the other hand, all doses of gamma rays induced significant increase in the percentage of chromosomal abnormalities which examined at different mitotic stages and the most frequent aberrations were c-metaphase and fragments. Data showed that cultivar Balady had the highest values of total chromosomal abnormalities at 1250 rad, while Sids-40 showed the highest value at 4000 rad. The biochemical studies exhibited changes in protein banding patterns; these changes included alterations in number of bands, band intensity and disappearance or appearance of certain bands. The occurred changes in RAPD profiles using eight primers following γ-irradiation treatment included variation in band intensity, loss of normal bands and appearance of new bands compared with the untreated plants. These results indicated that polymorphism and genomic template stability (GTS) value was affected at the above gamma doses. In conclusion, DNA polymorphisms detected by RAPD analysis could be used as a useful biomarker assay for the detection of genotoxic effects of γ-irradiation on plants.
Highlights
It was of specific interest to notice that the γ-irradiation dose of 4000 rad which caused the significant decrease in mitotic index (MI) in garlic cultivar Sids-40 gave the highest values of chromosomal abnormalities in the same cultivar
The present results further showed a high relation between mitotic index and the percentage of cells with chromosomal abnormalities in the tested garlic materials
The effect of different doses of gamma irradiation on cytogenetic and biochemical characters was studied in two Egyptian cultivars of garlic (Balady and Sids-40)
Summary
The effect of different doses of gamma irradiation on cytogenetic and biochemical characters was studied in two Egyptian cultivars of garlic (Balady and Sids-40). It was of specific interest to notice that the γ-irradiation dose of 4000 rad which caused the significant decrease in MI in Sids-40 garlic cultivar gave the highest values of chromosomal abnormalities in the same cultivar. The occurred changes in RAPD profiles using eight primers following γirradiation treatment included variation in band intensity, loss of normal bands and appearance of new bands compared with the untreated plants. These results indicated that polymorphism and genomic template stability (GTS) value was affected at the above gamma doses.
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