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

Genetic diversity in dormancy in Brassica napus secondary and exogenous gene transfer between species

Author YouQingBo
Tutor LuChangMing
School Central South University for Nationalities
Course Biochemistry and Molecular Biology
Keywords Brassica napus secondary dormancy GMO safety gene flow genetical stability
CLC S565.4
Type Master's thesis
Year 2013
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The genes of oilseed rape may introgress into other varieties or species viaspreading of the seed and pollen and environmental risk caused by gene introgressionwas widely concerned. The environmental risk caused by exogenous geneintrogression in oilseed rape was focused in this paper and genetic diversity ofsecondary dormancy in Brassica napus L. and the introgression of the male steriledgene into the Chinsee cabbage was highlighted. Secondary dormancy refers todormancy induced in originally non-dormant seeds because of unsuitableenvironmental conditions. It is responsible for the long-term existence of undergroundseed banks in rapeseed-producing areas and oilseed rape volunteers. In this study,genetic diversity of secondary dormancy was evaluated in49Brassica napus varietiesusing four seed burial methods and one PEG treatment. Significant differences insecondary dormancy were observed among different varieties of B. napus. Secondarydormancy varied from0to44%based on values obtained using the four burialmethods, with broad sense heritability ranging from40%to53%. Varieties exhibitingless than2%secondary dormancy accounted for45%of the49varieties, with38.8%of the varieties having secondary dormancy rates of2%~20%and16.3%, includingZaofeng4, Tower, ZS9, Hongyou2, and ZS5, with secondary dormancy rates of20%~40%. Broad sense heritability obtained under PEG treatment was82.1%. Usingcorrelation analysis, we found a significant positive correlation between differentperiods and depths in seeds subjected to burial treatment. For the PEG-induced seedsecondary dormancy data, a significant correlation was found with only some of theburial treatments. Burial experiments revealed that seeds of some varieties can enterinto deeper dormancy, and that these varieties may survive longer in soil.The strategyof avoiding the gene introgression caused by oilseed rape volunteers was provided inthis paper.Transgenic oilseed rape Ms8with male sterile gene barnase has been widelyproduced in Canada, but the introgression of exogenous genes into Chinese cabbage and the expression of exogenous genes have not been reported. This researchinvestigated the possibility of the barnase gene from transgenic B,napus c.v. Ms8introgressed into Brassica rapa varieties. In BC5generation of the backcross progeny,expression of the exogenous barnase gene was detected in anthers in B.rapa c.v.Shiyuehong as recurrent backcross parent. Male sterility was shown by organchemistry analysis and morphology observation. The quantity of barnase geneexpression was much lower in GM B.rapa Shiyuehong than in GM rape Ms8.

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