| The improvement of pod shatter resistance is important for the acceleration of machine harvest in oilseed rape. Previous studies suggested that variation of pod shatter resistance among oilseed rape exists widely. In this study, improved random impact test and ripping method were used to determine lines of Brassica napus and B. juncea. A cross between resistant and susceptible lines in B. napus was made and the inheritance of pod shatter resistance was investigated by applying major gene plus polygene mixed model and the QTLs mapped using SRAP and SSR marker. The result is as following:1.Improved random impact test and ripping method displayed similar results. Though the pod shatter resistance of B. juncea lines was higher than those of B. napus, it was still possible to identify lines with pod shatter resistance in B. napus. Both methods are simple and precise, suitable for use in most labs.2. A line named R1-1,which showed the highest resistance to pod shatter in all tested lines was obtained. Another two high lines: Hui1 and Hui2, which are the restorers of Nsa CMS, were also determined to be highly resistant.3. Improved random impact test were used to determine fifty lines of B. napus involved in Hubei provincial trial and in national trials of the middle reaches of Yangtze River of oilseed rape. The results indicated that pod shatter resistant indexes ranged from 0.020-0.470. Dividing pod shatter resistant indexes into five categories: >0.4, 0.3-0.4, 0.2-0.3, 0.1-0.2 and <0.1, the frequency distribution of these lines in the five categories was 5, 5, 10, 17 and 13, which indicated that the variation of pod shatter resistance among newly bred oilseed lines. By analyzing yield and quality of 10 lines which have high pod shatter resistance, Sanbei 98 and Zhongyou 112 were identified, which have passed the regional trial and could be used for machine harvesting.4. Inheritance of pod shatter resistance was investigated using Pl,P2,Fl,BCl,RBC1 and F2 generations of the cross of R1-1×R2 (B. napus) by applying major gene plus polygene mixed inheritance model.Results indicated that pod shattering of oilseed rape was controlled by two independent major genes with additive-dominance-epistatic effects plus polygenes with additive-dominance-epistatic effects (the E-0 model). Additive effects and dominance effects of the two major genes displayed similar results. One major gene could be affected by the other gene. Heritability values of the major genes of BC1,RBC1 and F2 populations were estimated as 50%, 49.96% and 49.45%, whereas those of polygenes were 48.29% and 25.27% in RBC1 and F2 populations, respectively. The environment variance was 25.28% in F2 indicating the environment factor contributed to the variance of pod shatter in B. napus.5. Using SRAP and SSR markers, a genetic linkage map of B. napus was constructed containing 19 linkage groups and 61 molecular markers,which covered 1013.9 cM of the whole genome. Quantitative traits loci (QTLs) associated with pod shatter resistance were identified by composite interval mapping using software WinQTLCart2.5. Seven QTLs were identified for pod shatter resistance on linkage groups of LG1, LG6, LG9, LG13 and LG16. Two QTLs with dominance effects, explained 55.12% and 22.1% of the total variation of pod shatter resistance, respectively.
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