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

Studies on Screening in Progeny Population of Distant Hybridization between Brassica Napus L. and Descurainia Sophia

Author ZhangLiJun
Tutor GuanRongZhan
School Nanjing Agricultural College
Course Genetics
Keywords Brassica napus Descurainia sophia distant hybridization hybrid progeny screen
CLC S565.4
Type Master's thesis
Year 2010
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Distant hybridization is an effective way to enrich new germplasm. It is significant to transfer Descurainia Sophia excellent characters to Brassica napus. The experiment was based on previous working materials in the intergeneric cross by our lab. The progenies of F3 and F4 generation were studied through morphological observation, cytological genetic observation, SSR molecular marker analysis and seed quality determination. Main results are as follows:1. Morphology in progenies of the distant hybridization. Genetic variations appeared in progenies of the distant hybridization. Common properties in the progenies at seedling stage included leaf rich with margin indentations, heart leaves etiolating, male sterility, corolla size and petal shape variations, etc. At harvesting stage, many variation types were observed, such as plant type, plant height, and the number of siliques per plant, 1000 seeds weight and seed weight per plant. In F3 generation,81 families were planted and 5 plants for each family were sampled for observation. Results showed that the plants with zigzag leaf margin accounted for 85.05%. And a few plants with heart leaves etiolating were observed. At flowering stage, the plants with above middle size corolla accounted for 85.53%. The average plant height was 129.7±19.65cm. The average number of siliques per plant was 389.5±100.32. The average 1000 seeds weight was 3.01±0.87g. Average seed weight per plant was 20.54±10.99g.In F4 generation,257 families were planted for evaluation, and 3 plants for each family were sampled for observation. At seedling stage and flowering stage, many variation types also appeared. At adult stage, the average plant height was 140.9±22.69cm. The average number of siliques per plant was 366.1±164.42. Average 1000 seeds weight was 3.36±0.50g. And the average seed weight per plant was 18.60±6.60g. F4 generation trait diversity was consistent with that of F3 generation.2. Observations of chromosome number and chromosome behavior. The average number of chromosomes in F3 and F4 populations was 35.6±3.67 and 35.3±4.74. Abnormal behaviors at meiosis stage were often observed in hybrid progenies, such as univalent, ring bivalents, bar bivalents, chromosome bridges, meiotic cycle asynchrony, and chromosome unequal distribution and so on.3. SSR molecular marker detection. SSR markers detection with 9 pairs of primers which were screened out from 42 pairs of primers showed that the average frequency of plants with bands characteristic of D. sophia in the F3 and F4 populations was 8.21% and 4.01% respectively, implying that the genetic composition from D.sophia in these progenies reduced gradually in the selfing process.4. Quality analysis for obtaining elite breeding materials. The sampled plants were harvested for further evaluation.13 yellow-seeded plants were selected from 430 F3 progenies, among which 4 elite plants were oil content more than 45%, erucic acid content less than 0.5% and glucosinolate content less than 30μmol/g. And then the 4 elite materials remained the same properties of good quality in F4 generation.24 elite individuals with yellow-seeded were newly obtained from 1025 F4 plants, and 8 of which were yellow-seeded, high oil content and double low contents materials. It is concluded that through this distant hybridization and progeny selection, new materials with desired quality traits can be obtained.In summary, through screening on morphological, cytological, molecular marker and quality analysis in progenies, the materials obtained with D. sophia genetic component introgression into B.napus will be benefit rapeseed breeding.

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