Improvement Of Erucic,Oleic And ?-linolenic Acid In Brassica Napus L.seeds Using Biotechnology

Rapeseed is one of the most important oil crops in China,but in recent years,due to the rapid increase in production costs and the intensified competition with imported oil products,the profits obtained from cultivating rapeseed have declined.The development of rapeseed industry gets stuck in bottleneck.Triacylglycerol(TAG)is the main component of lipids extracted from oilseeds,which consists of glycerol backbone and variable fatty acid chains.Compositions of fatty acids directly determine the physical and chemical properties,and thus quality and application of oil.Therefore,through the genetic regulation of certain genes,fatty acid compositions in rapeseed oil can be precisely manipulated and then satisfy the distinct requirements for oil in different industries and food processing methods,which is of great help for facilitating the comprehensive utilization and improving the economic value of rapeseed.FATTY ACID ELONGASE 1(FAE1),FATTY ACID DESATURASE 2(FAD2)and FATTY ACID DESATURASE 3(FAD3)are three key enzymes regulating fatty acid compositions.In this study,we set four research goals,eliminating or further improving erucic acid content in rapeseeds with high erucic acid content,elevating oleic acid content or ?-linolenic acid(ALA)content in “double-low” rapeseed.To achieve these goals,conventional breeding was engaged and the molecular biology tools,CRISPR-Cas9 gene editing and seed-specific overexpression were employed to regulate expression of genes encoding the above three enzymes in four rapeseed varieties with different genetic backgrounds.CRISPR/Cas9 construct was made to knock out Bn FAE1 in high-erucic acid rapeseeds.Transgenic plants,of which erucic acid was totally eliminated but oil content was nearly intact,were generated.To elevate the ALA content in rapeseed oil,we cloned FAD2 and FAD3 from high-ALA crop,Camelina sativa,and overexpressed them in “double-low” variety ZS11.30% ALA content was detected in the transgenic lines obtained.More notably,multiple lines with ALA content higher than 33% were screened from the hybrids of the overexpression lines.Bn FAD2 was silenced in higherucic acid rapeseeds and ZS11,which was expected to enhance the content of erucic acid and oleic acid,respectively.Whereas,significant alteration was observed in neither erucic acid nor oleic acid from T0 seeds,which requires further research and analysis in T1 lines.The improvement of fatty acids in rapeseed has been proposed for many years.In this study,we made use of biotechnological means to comprehensively manipulate fatty acid compositions of rapeseed oil from four perspectives.And whether the expression changes of several key genes involved in lipid metabolism would impact the oil content was investigated.Our research is expected to create elite lines and offer theoretical foundation for rapeseed quality breeding,significant for boosting the applicability and values of rapeseed oil.