عنوان مقاله [English]
Background and Objectives
Induced mutation has been used in wide range of horticultural crops in almost half of century. This approach has been made great opportunities for biotechnologists and plant breeder to produce new varieties with some new traits such as resistance to disease, tolerance to adverse environmental condition or even new horticultural characters in some crops. Optimization of physical and chemical mutagenesis agents dosage for induce mutation is the first asset to use this technique in breeding goals. This study was conducted to determine optimum doses of two mutagenesis agents including gamma radiation as physical agent and Ethyl Methane Sulphonate (EMS) as a chemical agent using saturated mutation technique. Also, mutant population produced and SSR markers were used to detect mutation in the mutant plantlets.
Material and Methods
After callus induction in tissue culture media containing NAA, BAP and meta topoline, produced callus were exposed to different doses of gamma radiation (0, 10,20,30,40, 50 Gy) or different Ethyl Methane Sulphonate (EMS) concentrations (0, 0.4,0.6,0.8,1,1.2 %). Then calluses transferred into shoot regeneration media. Dead Calli size and number of shoots generated in live callies were recorded. The regenerated shoots transferred into another tissue culture media for kiwifruit. Randomly some plantlets were selected to DNA extraction and SSR markers analysis. The SSR markers were detected using Genetic Analyzer.
Results and Discussion
Results indicated that as expected with increasing gamma radiation doses, the number of dead calli and size increased. The lowest dead callus was related to the control and the highest dead callus was belong to 50 Gy doseg. Regarding to LD50 index in mutation experiments, number of shoot generated in treated callus and SSR markers analysis, 50 Gy doses could be use as optimum radiation to produce acceptable mutation rate in kiwifruit callus. Ethyl Methane Sulphonate (EMS) as chemical mutagenesis agent showed different pattern in increasing shoot regeneration number but same trend with gamma radiation in dead callus and size. However, simple sequence repeat (SSR) markers did not work to show genetic diversity between control and treated plantlet but some mutations in Ethyl Methane Sulphonate treated population detected. This indicates that SSR markers are not suitable tool to detect mutation in EMS induced mutant. This can be explained by the mutation mechanism difference between gamma radiation and EMS. Meanwhile, regarding LD50, shoots generation in callus, 1% concentration of EMS can be use to produce reliable mutant population in kiwifruit plants.