Breeding Research Of EMS Chemical Mutation For Main Agronomic Characters In Strawberry

Chemical mutagenesis is an important breeding methods, due to its nontransgenic, easy to form a point mutation, and easily produced chromosome aberrations,has a very wide range of application in genetic breeding value. At present, there were few studies on the strawberry mutation breeding reported. Therefore, we should exploere an EMS induced mutation of high efficiency way for Strawberry's character improvement and new varieties(lines) to develop,which could provide references for further research. In this study, the plantlets and leaves of Strawberry varieties T1 and T2 were used as materials.These materials ware treated with EMS in 6 different doses(0%, 0.05%, 0.1%, 0.2%, 0.4%and 0.6%) for 12 hours. And then Cluster bud multiplication culture and rooting culture were made, and leaf was induced culture in the induction medium. It was found that after EMS treatment tissue culture and leaf are subject to different degrees of damage,and a certain percentage of variation was occyred on the field agronomic traits of strawberry.Specific results are as follows:(1) After EMS treatment, 10 kinds of variation were found in the M1 generation,which were short-stalked, tall-stalked, leaf curl, foliar shrinkage, foliar macular, leaf chlorosis, clusters of seedlings and loose plant type, and the total variation rate was 4.38%.(2) It showed that the higher the concentration of EMS the stronger physiological damage on material. Tested materials mortality increased with EMS concentration rised.The probability of variation of etiolation and vitrification was positively correlated with the concentration of EMS. When the concentration of EMS was 6%, the mortality of tissue culture seedling was significantly increased. When the concentration of EMS was more than 4% the mortality of leaf explants increased significantly. Mortality of three different EMS treatment methods: leaf induced culture > rooting culture > cluster bud multiplication culture.(3) After EMS treatment, different mutation spectrum and mutagenesis efficiency were found in different varieties(lines). There was more types of variation in T2 than that in T1,10 and 4 types of variation were found, respectively. The mutation rate of T2 was higher than T1, the reats of them were 5.67%and 2.72%, respectively.(4)The different mutation spectrum and mutagenesis efficiencies were found in different EMS treatment group. The mutagenic efficienciesin cultivation treatment of cluster buds proliferation leaf and root were 7.38%?2.98% and 0.67%, respectively.The variation type in root cultivation treatment is least, only observed useless mutations of short-stalked and leaf curl for breeding.There are 9 and 7 types of mutations were found in cluster bud proliferation and leaf, respectively, and the beneficial mutations of tall-stalked,precocious mutation and loose plant type appeared in both.(5)The mutagenesis efficiency of strawberry in different EMS concentration treatment group was different. Interaction of different treatments and concentration was found in the research. The tissue culture's mutagenesis efficiency was high in high concentration treatment group. In the low concentration treatment group, there were different results in different treatment methods. In the low concentration condition, there was no variation in rooting culture, while the variation was found that the different gene mutation effect is different in cluster bud multiplication culture. The mutation efficiency of leaf culture treatment group increased, firstly, and then decreased with the increase of EMS concentration. The highest mutagenesis rate was found in 0.2% concentration. If concentration was 0.6% all the leaf would be dead.(6) Cluster bud multiplication culture treatment materials have the lowest mortality rates, the most wide mutation spectrum range and the highest beneficial mutations efficiency; therefore, the cluster bud proliferation treatment is the best way in strawberry EMS mutation breeding. The results showed that the best treatment combination of T1 precocious mutation varieties(or lines) was to soak T1 tissue culture seedling with0.1%concentration of EMS and cluster bud multiplication culture after, the mutagenic efficiency was 8.99%. The best treatment combination of T2 varieties(or lines), including precocious mutation, tall-stalked and loose plant type, was to be treated with 0.4%concentration of EMS and cluster bud multiplication culture after, the three mutagenic efficiency were 7.76%, 6.48%and 11.35%, respectively.