Phenotypic and Molecular Responses of Wheat (Triticum aestivum L.) to Chronic Gamma Irradiation

The objectives of this study were to determine the effects of chronic gamma irradiation on growth and biochemical characteristics of wheat. Wheat plants were exposed to a 60Co gamma rays at doses ranging from 10 to 150 Gy for 3 weeks. Our results indicate that irradiation at 10–15 Gy enhanced plant growth as compared to non-irradiated wheat, while at high doses (>20 Gy) a significant decrease in wheat height was recorded. APX and CAT transcript levels were higher in plant irradiated at 12.5 Gy than in the controls. Also, the enzyme activities of APX and CAT and POD were increased by 12.5 Gy gamma irradiation. Chronic irradiation caused an increase in the total anthocyanin content. To assess whether anthocyanin biosynthesis-related genes were involved in the response to chronic gamma irradiation in wheat plants, we examined their expression under different doses of gamma rays. Levels of F3H, DFR, ANS transcripts increased due to chronic gamma irradiation, whereas CHS and CHI expression decreased. Total anthocyanin contents significantly increased after chronic irradiation. Furthermore, Ultra Performance Liquid Chromatography (UPLC) revealed that cyanidin 3-glucoside, one of the anthocyanin compounds, rapidly increased in wheat plants after chronic gamma irradiation. This study demonstrated that the growth of wheat plants and markers of biochemical activity were negatively influenced by chronic gamma irradiation in a dosedependent manner, although low-dose radiation showed stimulatory effects. Results from this study are very useful for future chronic gamma irradiation studies for the improvement of wheat varieties.