Dissertation
Dissertation > Agricultural Sciences > Crop > Economic crops > Oil crops > Rapeseed ( Brassica )

Preliminary Studies on 4 EMS-Induced Mutants in Brassica Napus L

Author HuangYongJuan
Tutor GuanRongZhan
School Nanjing Agricultural College
Course Genetics
Keywords Brassica napus L EMS Mutants Inheritance
CLC S565.4
Type Master's thesis
Year 2011
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The mutant library is important germplasm for the further studies on gene functions and rapeseed breeding. In this paper, preliminary genetic studies on 4 mutants including dwarf mutant, yellowish character, the white-mosaic flower and high oleat trait, were carried out. Main results are as follows:1) Inheritance of yellowish mutant m509:Its phenotypic performances are that the leaf and the stem color is yellowish from the cotyledon stage; At mature stage, all the agronomic traits of the yellowish mutant were poor relatively to its wild type.The leaf of F1 between m509 and Tapidor showed green leaves, and in this F2 population, segregation ratio of normal green plants vs yellowish plants was 3:1 withχ2 value 0.82 (P=0.05), indicating that the yellowish mutation is controlled by a single recessive nuclear gene.2) Inheritance of white-mosaic flower mutant m381:Its flower of 2-4 petals is white-mosaic with 1/3 one petal white; Compared with its wild type, its main stem length was shorter and seed number per silique was smaller.The flower of F1 between m381 and Tapidor showed white-mosaic, and in this F2 population, segregation ratio of yellow flower plants to white-mosaic plants was 1:3 withχ2 value 0.87 (P=0.05), indicating that the white-mosaic mutation is controlled by a single dominant gene.3) Inheritance of dwarf mutant m176:Its average plant height was about 89.6 cm, The leaf was deeply green, growing creepingly before flowering. In F2 population compared with common plants, the dwarf mutant branching height was lowered, main stem length is shorter and seed number per silique was smaller. The plant height of F1 between m176 and wester was slightly lower than the dwarf parent, The F2 population height have seperated and make frequency histogram with the data of F2. Based on their value in the bottom and refered the parent average height, set 105 cm as the boundary points to distinguish tall and dwarf plants. The plants statistics showed that the tall plants and dwarf plants was 3:1 withχ2 value 1.68 (P=0.05), indicating that dwarf character is controlled by a single dominant gene. ELISA assay for GA3 content in leaves was carried out at seedlingly stage. The content of GA3 was significantly less than the wild type, indicating that the dwarf mutant is a GA-deficient mutant.4) Cloning and sequence analysis of FAD2 gene in M2080-3:The mutant M2080-3 oleate content reached 75.02% and was higher than the wild type by 10 percent. Its agronomic traits showed no significant difference from the wild type. High oleic acid content of 2080-3 (75.02%) may be caused by the mutation in FAD2 gene. So the FAD2 genes of the high oleate mutant M2080-3 was cloned, the result showed the wild type including three BnFAD2 genes (label BnFAD2Ⅰ, BnFAD2Ⅱ-Ⅰand BnFAD2Ⅱ-Ⅱ). Compared with the wild type,41 bases in the BnFAD2Ⅱ-Ⅰgene of 2080-3 had been mutated, leading to the change of 15 amino acids, of which 11 amino acids taken place in the conserved regions which was considered to be the catalytic center of enzyme. Furthermore 63 bases in the BnFAD2Ⅱ-Ⅱgene changed, leading to the complete protein could not be translated. The mutations of the BnFAD2Ⅱ-Ⅰand BnFAD2Ⅱ-Ⅱlead to increased oleic acid content of M2080-3.

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