Induction of genetic variability with gamma radiation and detection of DNA polymorphisms among radiomutants using sequence-related amplified polymorphism markers in Gaillardia pulchella Foug. plants

Background Developing novel ornamental varieties with improved floral characterization is the main aim of floriculture. Biotechnological techniques linked to classical breeding methods have been applied for modifying flower color. Objective This investigation was carried out in the nursery of the Ornamental Horticulture Department, Faculty of Agriculture, Cairo University, Egypt, during two successive generations, 2019/2020 and 2020/2021, to assess the effects of gamma irradiation (γ) on vegetative growth, flowering parameters, abnormalities, and induced changes at the DNA level between two mutative generations (MG1 and MG2) of Gaillardia pulchella Foug. plants. Materials and methods Seeds of G. pulchella (local red) were irradiated at Atomic Energy Commission-united irradiation-Gamma, The Egyptian Atomic Energy Authority (EAEA), Nasr City, Cairo, Egypt, by six doses of γ-irradiation (10, 20, 30, 40, 50, and 60 Gy), using Gamma-1 type cobalt60, at a dose rate of 1.107 KGy/h. Results and conclusion The results revealed that low gamma doses (10 and 20 Gy) had significant effects on vegetative growth, that is, plant height and the number of branches, as compared with the control, giving the tallest plants with the highest number of branches. The high doses (50 and 60 Gy) delayed flowering compared with untreated plants and other gamma doses. In contrast, low doses induced early flowering and increased the number of flowers. All doses of gamma rays induced mutants in leaf morphology, inflorescence color, shape, and deformation; the largest number of these mutants was obtained from a high dose of 60 Gy. On the contrary, sequence-related amplified polymorphism analysis produced 32 loci, of which 12 (37.50%) were polymorphic. Jaccard’s coefficients of dissimilarity ranged from 0.69 to 0.96. In a dendrogram constructed depending on genetic identity coefficients, the mutants were classified into three major groups: the first group (I) was composed of 10-, 20-, 30-, and 40-Gy mutants. The second group (II) included 50- and 60-Gy mutants. The third group (III) contained only the control. Therefore, it was concluded that treatment of G. pulchella seeds with gamma rays led to the induction of a sufficient number of mutations. In addition, the sequence-related amplified polymorphism marker is considered to be an important tool in the identification of mutants. Consequently, these mutants can be used in breeding programs to improve G. pulchella plants.