Radiosensitivity Test to Determine the Suitable Dose of Induce Mutation in Saffron (Crocus sativus L.)

Saffron is a triploid and sterile plant having no or little genetic variation. Mutation induction is a way of increasing genetic diversity in vegetatively propagated plants. The first step in the mutation induction is to perform a radio-sensitivity test for determining the proper dose of gamma ray. Therefore, the aim of this study was to test the sensitivity of different doses of gamma ray in two conditions of cold and non-cold treatment of saffron corms. For this purpose, a factorial experiment with two factors including cold pre-treatment (cold and non-cold) and different doses of gamma ray (0, 5, 10, 15, 20 and 25 Gy) was conducted in a randomized complete block design with three replications. Growth and morphological characteristics such as plant height, number of leaves per plant, leaf dry weight, sprouting rate and percentage in the first year (MV1), and attributes related to daughter corms and flower yield, such as mean height of the stigma and dry weight of the stigma in the second year (MV2) were measured. The results of the study showed that the effect of cold treatment, radiation and their interaction was statistically significant, with the increase in gamma dose, most of the traits decreased significantly compared to the control. The radio-sensitivity test for the mean of plant height and sprouting rate and percentage, corm weight in two levels of pre-cold treatments showed that 50% survival was in the range of 15±2 Gray. According to the radio-sensitivity test, the number of leaves per plant was less susceptible to gamma rays. In order to study the genetic diversity of the gamma-irradiated saffron. The mutated samples of saffron were evaluated using RAPD and ISSR molecular markers. Cluster analysis was performed using the UPGMA method for both marker systems. The results showed that there was polymorphism between the control samples and radiated samples. In general, the results showed that the RAPD and ISSR markers could detect the polymorphic mutants and identify saffron mutants.