Effect of EMS Ethyl Methane Sulfonate (EMS) mutagen on Iranian rose (Rosa persica Michx) to generate morphological variation

Introduction:

Genetic diversity is one of the major goals of plant breeding. Mutation induction is a method to increase genetic variety that is used in plant breeding along with selection, recombination or a combination of the both. Rosa persica Michx can serve as a valuable genetic resource for breeding programs, especially due to the market demand for variety in rose cultivars as well as its drought resistance.  In two independent experiments, this study examined the effect of ethyl methane sulfonate (EMS) as a chemical mutagen on seed germination and seedling characteristics of Rosa persica. 

Materials and Methods:

 The seeds of Rosa persica Mich.seeds were collected from an adult shrub on the Arak University campus, Karbala St., Sardasht (34° N, 49.6° E) and an altitude of 1872 m above sea level during mid-summer. The seeds were separated from the hips by a sharp scalpel and the damaged and abnormal seeds were removed. Before applying the cold stratification, the seeds were washed for several hours and then placed in layers of wet sand at 4 ° C for 60 days.First, the effects of 0, 0.2, and 0.3% EMS at 4, 8 and 12 hours on seed germination characteristics were examined. Second, 0, 0.2, and 0.3 concentrations of EMS at 4 and 8 hours were studied on reproductive buds. Seed germination characteristics such as final germination percentage, germination rate index, coefficient velocity germination, germination rate, mean daily germination, daily germination speed, mean germination rate, germination index, seed vigor, seed dormancy and seedling vegetative traits such as stem lengths, root lengths, and leaf number are evaluated at first experiment. In second experiment, flower diameter, flower opening rate, number of necrotic buds and the number of seeds in each hip were measured. 

Results and Discussion:

The results showed that increasing the concentration of EMS and the time of seed treatment caused a further decrease in germination indices. In 0.3% EMS treatment for 8 hours on seeds, traits such as germination percentage, germination rate index and daily germination were reduced to zero. According to the results of the second experiment, leaf and seedling lengths were longer at 0.2 and 0.3% EMS concentrations and at 4 h incubation. There was a decline in the number of seeds per hip and an increase in necrotic buds with increasing concentration and time of EMS application. In order to succeed in a breeding program using mutagenic methods, the appropriate concentration and time must first be optimized. To determine the best concentration of mutagens, there are two important factors to consider: first, that the concentration should not be so high as to destroy plants, and second, that the applied concentration should be selected moderately. Although, that the frequency of mutations occurs sufficiently. 

Conclusion:

In order to induce a positive mutation and diversity in Iranian roses for the purpose of introducing a new cultivar, seed treatment with a concentration of 0.3% EMS and an incubation time of 4 h is recommended. It is also recommended to apply a concentration of 0.2% EMS on the reproductive buds for 4 h to induce mutations. Keywords: Seed, breeding, germination, mutation, ornamental plant