Comparing Effectiveness Of Different Mutagens For Seed Quality And Analysis Of Mutants In Brassica Napus

Induced mutagenesis has become one of most important tool in plant biology and breeding for changing plant traits, studying gene function, and locating genes on chromosomes. The use of ionizing radiation, chemical mutagens and space environment for inducing variation is well established. However, the ionizing radiations, chemical mutagens and space environment have different efficiency in inducing mutations as they bring about both chromosome aberrations and gene mutations.In order to find the best induced mutagenesis and dosage to improve seeds quality of Brassica napus, Comparing effectiveness of different mutagens (gamma rays, Ethyl methane sulphonate and space environment) for seed quality in Brassica napus were studied in three B. napus lines. Then, the variation analysis of seeds compositions were described in the progeny to prove the feasibility of improving rapeseed seeds quality by induced mutagenesis. At the same time, some high oleic acid, high protein, low linolenic acid mutants were expected to be screened. Furthermore, we have obtained one dwarf mutant and the other one chlorophyll-deficient seedling with yellow-green leaves mutant from the B. napus inbred line T6 through chemical mutagen ethylmethane sulfonate (EMS). Genetic analysis and mapping of these two mutants were carried out. The main results were as follows:1. Comparing effectiveness of different mutagens (gamma rays, Ethyl methane sulphonate and space environment) for seed quality in B. napusThree different B. napus lines were treated with y ray (800 Gy,1000 Gy and 1200 Gy), EMS (0.5%,1.0% and 1.5%) and space radiation respectively. Analysis of the seeds compositions of M3 seeds suggested that both y ray EMS can increase the variation of seeds composition. However, different variation was detected between different treated methods. For rapeseed seeds compositions breeding,1.5% EMS was more effective than other ways in the black seeds lines. At the same time, lower dose of y ray (800 Gy) and EMS (0.5%) was more preferable for yellow seed lines.2. The effects of bleomycin on microspore embryogenesis in B. napusThe effects of bleomycin on microspore embryogenesis and cell division were investigated using three concentrations of bleomycin in five semi-winter genotypes of B. napus viz. T8, T10, B409, P30, and DH1142. Inclusion of bleomycin in the culture medium at a concentration of 0.1μg ml-1 for 30 min significantly improved embryo production and cell division in all five genotypes. Embryo production was induced at rates two-and four-fold higher than controls after bleomycin treatment. Fifty plants regenerated by microspore embryogenesis treated with bleomycin in addition to non-treated controls of T8, T10, and B409 were selected for AFLP analysis. The results suggest that microspore culture is capable of producing 0.095% to 0.114% genetic variation, and there was no effect of bleomycin treatment on genetic stabilisation of doubled haploid populations versus the non-treated control.3. The research of one dwarf mutantIn the present study, we have obtained one dwarf mutant (bnaC.dwf) from the B. napus inbred line T6 through chemical mutagen ethyl methanesulfonate (EMS). We have determined the phenotypic effects and genetic characteristics of dwarf mutant(bnaC.dwf). Genetic analysis revealed that one recessive gene is responsible for controlling the phenotypic expression of dwarf mutant. The dwarf mutant was insensitive to exogenous GA3 for plant height, suggesting that it is significantly playing a crucial role in the gibberellins response pathway. Amplified Fragment Length Polymorphism (AFLP) technique was applied for selecting markers linked to the BnaC.DWF gene which assisted in screening of dwarf and normal individuals in the BC4 population. We have identified nine AFLP markers linked to the BnaC.DWF gene, and four AFLP markers were successfully converted into Sequence Characterised Amplified Region (SCAR) markers. The BnaC.DWF gene was further mapped to the linkage region C8 by Simple Sequence Repeat (SSR) markers.4. The research of one chlorophyll-deficient seedling with yellow-green leaves mutantIn the present study, we have obtained one chlorophyll-deficient seedling with yellow-green leaves mutant (bnaC.ygl) from the B. napus inbred line T6 through chemical mutagen ethyl methanesulfonate (EMS). We have determined the phenotypic effects and genetic characteristics of chlorophyll-deficient seedling mutant (bnaC.ygl). Genetic analysis revealed that one recessive gene is responsible for controlling the phenotypic expression of dwarf mutant. Amplified Fragment Length Polymorphism (AFLP) technique was applied for selecting markers linked to the BnaC.DWF gene which assisted in screening of dwarf and normal individuals in the BC4 population. We have identified nine AFLP markers linked to the BnaC.DWF gene, and four AFLP markers were successfully converted into Sequence Characterised Amplified Region (SCAR) markers. The BnaC.DWF gene was further mapped to the linkage region C8 by Simple Sequence Repeat (SSR) markers.