Effects Of ⁶⁰Co-γ、EMS And Colchicine On Mutagenesis Of Capsicum Frutescens Seeds

In this study,self-bred’Zhongnong qianjin hong’of capsicum frutescens maxim was used as material,and the seeds of capsicum frutescens maxim were treated with cobalt(⁶⁰Co-γ),ethyl methyl sulfonate（EMS）and colchicine,the suitable semi-lethal doses of mutagenesis were selected and determined respectively,and the germination process and dynamic cytology of embryo were observed,combining with the situation of unearthed after sowing,morphological and physiological characteristics of the seedlings,and identifying the molecular markers of the mutant seedlings,in order to obtain the mutant plants,enrich the germplasm resources and widen the variation types of capsicum frutescens maxim,it will enrich the existing theory and practice for genetic improvement and new variety breeding of capsicum frutescens.The main findings are as follows:1.The germination power（germination potential,germination rate）,germination index and emergence rate of capsicum frutescens seed decreased with the increase of mutation intensity,1.40%EMS treatment（53.06%）>0.03%colchicine treatment（50.83%）>400Gy radiation treatment（50.28%）.In this case,the seedling rate of the three mutation methods was about half of the control.Based on the linear equation between the mutation intensity and the seedling rate,combined with the growth status of the seedlings in each treatment,the results showed that the radiation dose was 377.14Gy,the EMS concentration was 1.36%,,and the colchicine concentration was 0.036%.2.When the radiation dose was 100Gy and the EMS concentration was 0.60%,the seeds of capsicum frutescens were treated by ⁶⁰Co-γand EMS.The superior mutant plants were found to be more robust than the control plants,with dense leaf color,thick stem,more leaves and internodes,and better plant growth,rapid growth,with the increase of mutagenic dose,the growth potential gradually weakened,the rate of malformations increased,the seedling was small,the number of leaves and internodes gradually decreased,the growth was slow.Low mutagenic dose can promote the growth of plant,while high dose can inhibit it.3.There was a negative correlation between the contents of chlorophyll a,chlorophyll b,chloroplast pigment content and carotenoid in the mature seedlings and the mutagenic dose,and the contents of chlorophyll were higher than the contents of carotenoid,the content of chlorophyll a was higher than that of chlorophyll b,and the content of MDA and relative electric conductivity increased with the increase of the dose,the activities of SOD,POD,CAT and the content of soluble sugar in leaves increased at first and then decreased,enzyme activity and soluble sugar content were higher than 0.03%colchicine treatment and 1.40%EMS treatment in 400Gy irradiation,and the maximum value appeared under each mutagenesis method.4.After the seeds were treated by three methods,the ultrastructure of the embryo of the control seeds was normal during germination,and the ultrastructure of the embryo changed after irradiation,with the increase of radiation dose and the continuation of radiation effect,the ultrastructure of embryo was damaged seriously,the cells were atrophied,long and shriveled,the rate of cell wall distortion was increased,the mitochondria expanded into spherical shape,and the plasma membrane was broken.The observation of epidermal cells and stomatal apparatus of leaves under light microscope showed that the length of guard cells of upper and lower epidermis first increased and then decreased with the increase of mutagenic dose,showing a normal distribution trend,and the number of stomata of upper epidermis was less than that of lower epidermis,the number of stomata increased with the dose of mutagenesis.By scanning electron microscopy,most of the epidermal cells were irregular,followed by unequal cells,stomata were elliptic,stomata were basically stomatal complexes,other epidermal cells were lower than stomatal complexes,stomata were in open state.5.8 radiation materials,6 EMS mutagens,5 colchicine mutagens and control plants were detected by SSR molecular markers,primers were screened and PCR amplification was performed,it was found that the mutagens could be distinguished from the control on the spectral band,which basically indicated that the mutagens had changed at the DNA level.In the results of polymorphic primer amplification,the length of the amplified fragment was 50～300bp.The polymorphic rate of EMS>radiation>colchicine was 100%,and the lowest was 50%The average number of bands per pair of primers was higher than EMS and higher than colchicine,and the main types of band mutation were"new band","mixed band"and"band deletion".