The Main Metabolites Analysis And Functional Verification Of DGAT,SAD And FAD During The Development Of Oil Tea Seeds (Camellia Oleifera)

Camellia oleifera abel.,which originated in China,is a natural high quality woody oil crops.The edible oil extracted from its seeds is rich in high quality fatty acids and has high nutritional value.In this study,we measured the storage materials,oil content and fatty acid components of camellia oleifera at different development stages and combining the transcriptome data at six development stages,identifing the key oil production pathways and genes for seed development.By analyzing the fatty acid biosynthesis and the assembly of triacylglycerol(TAG),the synthesis of triacylglycerol and the mutual transformation between oleic acid,linoleic acid and linolenic acid,the gene expression rules in the process of oil accumulation in camellia seed were revealed.In this study,DGAT,SAD and FAD genes that affect oil synthesis during camellia oleifera development were comprehensively analyzed,and the synthesis of triacylglycerol and the composition mechanism of high oleic acid,low linoleic acid and linolenic acid during camellia oleifera development were explained.In addition,this study also takes advantage of the genetically modified yeast technology and tobacco leaf instantaneous expression means to verify the function of fat synthesis of candidate genes,explain from the Angle of molecular level in the process of the development of tea seed synthesis mechanism,the high proportion of the oil and fatty acids as the research and breeding of high oil and high quality camellia varieties to provide theoretical basis and guidance.The main research work and results are summarized as follows:1.Tea oil is mainly composed of 8.79% palmitic acid(C16:0),0.17% fatty acid(C16:1)1.71%,stearic acid(C18:0),79.09% oleic acid(C18:1),9.82% linoleic acid(C18:2),and0.42% linolenic acid(C18:3).With the development of seeds maturing,the total fatty acid content to accumulate,in the mature stage was 155.5 mg/g.The oleic acid content was increased,and the proportion of oleic acid to total unsaturated fatty acids was 77.6%in the mature stage.Palmitic acid,linoleic acid and linolenic acid content changes gradually reduced.The content of total fatty acids in the shell of camellia olefolia seed decreased from 1.76 mg/g in the first development period to 0.60 mg/g in the sixth development period.2.The main storage substances in camellia seeds: the contents of soluble sugar,increased in the early stage and decreased rapidly in the last stage.There was a negative correlation between fatty acid accumulation and soluble total sugar.Soluble starch and soluble protein showed an increasing trend.But Camellia seed fruit shell changes in the opposite direction.The vitamin E in camellia seeds is mainly in the form of α-tocopherol.The content change of α-tocopherol generally shows an increasing trend during the ripening of seeds,small amounts of γ-tocopherol are present in predevelopment.α-tocopherol reaches a maximum value of 18.9 μg/g during the ripening period.3.The two DGAT genes,Co DGAT1 and Co DGAT2,were amplified and located in the endoplasmic reticulum.The quantitative results of camellia seeds at different development stages showed that the expression of Co DGAT1 was on the rise and that of Co DGAT2 was on the decline.The accumulation of triacylglycerol was significantly increased when expressed in the synthetic triacylglycerol deficient yeast H1246 cells.4.The two amplified SAD genes of camellia seeds,Co SAD1 and Co SAD2,were located in the chloroplast.The quantitative results of these two genes at different development stages of camellia seeds showed that their expression increased first and then decreased.The expression of these two genes in wild yeast YPH499 a cells significantly increased the accumulation of oleic acid.5.The two FAD genes,CoFAD2 and CoFAD3,were amplified from camellia seeds,and the quantitative results of these two genes at different development stages of camellia seeds showed a decreasing trend in their expression.Transient expression of these two genes into tobacco leaves significantly increased the accumulation of linoleic acid and linolenic acid in tobacco leaves.