Identification Of Aromatic Components And Mechanism Of Aroma Formation Of Narcissus Spp.

Narcissus spp.is the world-famous ornamental flowers for its gorgeous colors and graceful appearance,Narcissus spp.has abundant cultivars,but only few of them has fragrance,Narcissus ’Bridal Crown’ and ’Mount Hood’ were choosen as the marterials to study the difference of aromatic component and mechanism of aroma formation of different cultivars of Narcissus spp..The aromatic components and contents in four flower phases of ’Bridal Crown’ and ’Mount Hood’ were analyzed by Headspace Solid phase Micro extraction and gas chromatography-mass spectrometry.Changes of content of benzyl alcohol and activity of AAT in four flower phases of ’Bridal Crown’ and ’Mount Hood’ were analyzed by GC-MS.Besides,AAT gene was cloned and its expression patterns were studied.The main results were as follows:1.The aromatic components and contents were significantly different in different developmental stages of Narcissus ’Bridal Crown’ and ’Mount Hood’.The main aromatic components of Narcissus ’Bridal Crown’ were terpenes,and the second was esters and alcohols,including(Z)-β-ocimene,Benzyl acetate,Benzoic acid,methyl ester,Allo-ocimene,Eucalyptol.The greatest characteristic aromatic components were Benzyl acetate and(Z)-β-ocimene.The main aromatic components of ’Mount Hood’ were terpenes,and the second was alcohols,including(Z)-β-ocimene,Allo-ocimene,P-Myrcene,Benzene,1,4-dimethoxy-,Eucalyptol.The greatest characteristic aromatic components were(Z)-β-ocimene.The biggest difference in aromatic component between ’Bridal Crown’ and ’Mount Hood’ was esters compounds,which had played a critical role of aroma formation of Narcissus spp.,Benzyl acetate is the key aromatic component which may be result in that’Bridal Crown’ has more fragrance than ’Mount Hood’.2.We determined the Changes of activity of AAT in four flower phases of Narcissus ’Bridal Crown’ and ’Mount Hood’ by DTNB colormetric method,the results showed that there were positive correlation between the activity of AAT and content of esters compounds in’Bridal Crown’,while there were no obvious correlation between the activity of AAT and esters compounds in’Mount Hood’.3.The content of benzyl alcohol in four flower phases of Narcissus ’Bridal Crown’ and ’Mount Hood’ were analyzed by GC-MS.Benzyl alcohol was detected in four flower phases of Narcissus ’Bridal Crown’,while there were no benzyl alcohol in ’Mount Hood’.Besides,there were positive correlation between the content of benzyl alcohol and content of estes compounds in’Bridal Crown’.’Mount Hood’can’t synthetic benzyl acetate for lack of benzyl alcohol.The synthesis of benzyl acetate was affected by benzyl alcohol and the activity of AAT.Sufficient supply of benzyl alcohol substrate and a high activity of AAT enzyme is the key to synthetic benzyl acetate.4.We determind the content of benzyl acetate in four flower phases of Narcissus’Mount Hood’ before and after benzyl alcohol treatment,the results showed that benzyl acetate was detected in four flower phases of Narcissus ’Mount Hood’ in the case of exogenous benzyl alcohol is enough,which indicated that ’Mount Hood’ also has the ability of synthesis of benzyl acetate.Study the solution to solve the problem of insufficient supply of benzyl alcohol substrate of light fragrant narcissus,which is the key to make the light fragrant european narcissus with rich sweetness.5.The alcohol acyltransferase gene(AAT)was isolated from Narcissus ’Bridal Grown’and ’Mount Hood’,named as NtAAT-BC and NtAAT-MD.The sequence showed that it was 98%amino acid homology between NtAAT-BC and NtAAT-MD,but they have a less amino acid homology with others plants.The two genes both contains HXXXD and FGWG conserved motif.6.The expression model of AAT in four flower phases of Narcissus ’Bridal Crown’ and ’Mount Hood’ were analyzed by qPCR.The results showd that the two gene had expressed in four flower phases of the two species,and also had a difference between the four stages and varieties.Meanwhile,the expression model of NtAAT-BC had a positive correlation between the changes of activity of AAT and content of estes compounds,so we deduced that AAT is likely to have played a role in synthesis of esters compounds.