Effect of Mutagenic Treatments on Somaclonal Variation in Wheat (Triticum aestivum L.)

Different wheat genotypes were treated with gamma-rays, sodium azide (SA) and EMS before tissue culture and immature embryos from M₁ plants or plants shortly after exposure to gamma-rays were used to initiate callus culture. Thousands of plants were regenerated and used to investigate the effect of mutagenic treatments on the regenerated plants and somaclonal variation in the M₃R₂ and M₂R₂ generations. The results showed that mutagen-induced damage in terms of reduction in plant height, fertility and spike length were not outstanding in the regenerated plants as compared with the untreated control. In the M₃R₂ generation, only SA treatment had significantly higher frequencies of somaclonal variations than the control. Increases in the variation frequencies were observed when explant embryos were irradiated with 2.5 and 5 gy gamma-rays and the highest frequency appeared when embryos were exposed to 5 gy gamma-rays on the 5th day after anthesis. Increased variation spectra also resulted from mutagenic treatments and most of the variants recovered were unsuitable for plant improvement.