Improvement Of Rapeseed Fatty Acid Composition Through Mutagensis And Inheritance Of Oleic Acid Content

The rapeseed oil quality is primarily determined by its fatty acid composition. It is important for improving the rapeseed oil quality through increasing the oleic acid content and reducing the content of saturated fatty acids and linolenic acid. The utilization of the mutagensis is an effective method for fatty acid breeding.The objectives of this research were to study the seeds of Brassica napus treated with radiation mutagen and chemical mutagen and compare the effects of these two mutagens on the four different lines. Then, the variation analysis of fatty acid composition in the progeny were described to prove the feasibility of improve rapeseed oil quality. At the same time, some high oleic acid, low saturated fatty acid, low linolenic acid mutants were expected to be screened. Furthermore, the inheritance of oleic acid content was investigated. The results were as follows:1. Four different Brassica napus lines were treated with 1.5%(w/v) EMS and 25.8C/Kg ~60Co-γ ray respectively. In the M1 plants, line 02-3858 was tolerant to both EMS and γ-ray treatment. Line 02-3705 was tolerant to EMS treatment but sensitive to γ-ray treatment. Line 02-3761 was tolerant to γ-ray treatment but sensitive to EMS treatment. Line 02-3837 was sensitive to both EMS and γ-ray treatment. Analysis of the fatty acids of M2 seeds suggested that both γ-ray and EMS can increase the variation of fatty acid composition. Compared with γ-ray, EMS produced more valuable variation. For rapeseed fatty acid breeding, EMS was more effective than γ-ray.2. M1 plants of Huashuang-3 treated with EMS were self-pollinated to obtain M2 seeds. Analysis of the fatty acids of M2 seeds suggested the variation ranges of the fatty acids in M2 seeds were wider than those in contrasts. Erucic acid (C22:l) showed more significant differences among progeny than oleic acid (C18:l) and linolenic acid (C18:3). Relationships among fatty acids were examined by simple correlation. Highest negative correlation was between erucic acid and oleic acid. Oleic acid content was significantly negatively correlated with palmitic acid, linoleic acid and linolenic acid. The same results were obtained in the analysis of the fatty acids of M3, M4, M5 seeds. Six high oleic acid mutants, four low saturated fatty acid mutants and five low linolenic acid mutants were screened in M5 seeds. The results shows that the utilizationof mutagensis can increase the variation of the fatty acids and high oleic acid, low saturated fatty acid and low linolenic acid mutants can be screened.3. Reciprocal crosses were made between low erucic acid Brassica napus lines 6111(68.67% C18:l in the seed oil ) and 6117(53.72% in the seed oil). Populations of Fi, Fir, F2, F2r, BC1F1 and BC]Fir were developed. The oleic acid contents of the Fi seeds were high and the oleic acid contents of the Fi seeds were low. In F2, F2r, BC1F1 and BCiFir, oil acid did not segregate following a certain ratio, but distributed continuously. In this research partial maternal effect for oleic acid content was found from reciprocal crosses. It was estimated that the inheritance of oleic acid content was controlled by polygenes.