| Camelina sativa has been considered as a kind of low-input crop,with strong resistance to stress,a promising alternative oilseed crop in many regions,such as food,feed and industrial applications.However,the high content of polyunsaturated fatty acids in camelina sativa makes it oxidized easily and unstable.Therefore,improving the fatty acid composition and the antioxidant properties has always been the research focus of camelina sativa.It is necessary for enhancing the antioxidant and stability of camelina sativa oil to explore the influences of exogenous hormones on fatty acid composition and tocopherol synthetic pathway.In this study,Four vegetable oils with different fatty acid profiles(perilla oil,camelina sativa oil,linseed oil,rapeseed oil)were chosen to carry on Schaal oven accelerated oxidation assay.It was aimed to study correlations among inherent influence factors like fatty acid compositions and tocopherols,and analyze the change rules of the primary and secondary oxidation products.In addition,the effects of exogenous gibberellin3(GA3)and methyl jasmonate(MeJA)on the modification of fatty acid compositions,and the accumulation of tocopherol and the related gene expression were studied by real-time PCR.The main results were as follows:Firstly,The oxidative stabilities of the four vegetable oils with different fatty acid profiles were in the order of rapeseed oil>camelina sativa oil>linseed oil>perilla oil,evaluated by rancimat oil oxidation stabilizer,being consistent with the calculated oxidizability(COX)value.Schaal oven accelerated oxidation assay was carried.It was aimed to study correlations among inherent influence factors like fatty acid compositions and tocopherols.The results showed that:the higher α-T content of rapeseed oil and camelina sativa oil,showing the faster degradation rate of total tocopherol and α-tocopherol equivalent value on them,followed by Perilla oil and linseed oil.Otherwise,with similar fatty acid composition between camelina sativa oil and linseed oil,the oxidative stability of camelina sativa oil was slightly higher than that of linseed oil.The higher levels of total tocopherol and α-tocopherol equivalent in camelina sativa oil,showing faster degradation.The higher the content of polyunsaturated fatty acids,the more rapid growth of peroxide value,anisidine value and total oxidation value.Therefore,fatty acid composition and tocopherol content had a certain impact on oil oxidation stability.Secondly,the effects of exogenous gibberellin3(GA3)and methyl jasmonate(MeJA)on the modification of fatty acid compositions,and the accumulation of tocopherol were studied by crop chemical regulation.The results showed that GA3 applications during seed filling had negative impacts on fatty acid composition and the accumulation of tocopherol.However,MeJA applications had positive influences on improving the stability of seed oil oxidation and biodiesel quality,increasing the proportion of saturated fatty acids and the total tocopherol content and α-tocopherol equivalents in oil significantly,reducing the unsaturated fatty acid content effectively.Finally,based on the evaluation of fatty acids and the total tocopherol content,the treatments of 7 DAF/21 DAF+GA3 and 7 DAF/21 DAF+MeJA were screened to be carried on fatty acid metabolism by qPCR.The results showed that genes of FAD2 were up-regulated,reducing the accumulation of oleic acid,and the expression of HPT,HPPD and y-TMT was down-regulated and the synthesis of tocopherol was hindered,which were not helpful to improve the oxidation resistance of camelina sativa oil.However,the treatment of 21 DAF+MeJA,effectively inhibited the expression of FAD2-1,FAD2-3 and FAD3,promoting the accumulation of oleic acid.With the expression of HPT,HPPD and y-TMT gene significantly up-regulated,the content of tocopherol and α-tocopherol in the seeds of cameina sativa was significantly improved,which was beneficial to improve the antioxidant capacity of camelina sativa seed oil. |
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