Preliminary Research On The Effect Of Earth Up Softening Cultivation To The Synthesis Of Volatile Substances In Water Dropwort(Oenanthe Stolonifera(Roxb)Wall.)

Water dropwort(Oenanthe stolonifera(Roxb)Wall.)is a perennial aquatic herb and one of the most important aquatic vegetables in China.It is mainly planted in Jiangsu,Zhejiang,Anhui and other places.Water dropwort contains high dietary fiber,flavonoids and other functional substances,and has diuretic,digestive,blood lipid lowering,blood pressure and other medicinal value.Water dropwort has a special flavor,which is hard for some consumers to accept.According to the research findings,the main influencing factors of water dropwort flavor are γ-terpiene(terpineoil flavor)and caryophyllene(grass fragrance).Cultivation with earth up softening is a common cultivation method of water dropwort,and the taste of water dropwort after earth up softening cultivation is fresh and fragrant.However,there are relatively few studies on volatile substances in water dropwort cultivation with earth up softening cultivation,and there are no reports on the formation mechanism of volatile substances in water dropwort.In this paper,the effect of soft cultivation on the flavor of water dropwort was studied,and transcriptome sequencing was used to explore the formation mechanism of the volatile substances of water dropwort,so as to provide a theoretical basis for the research on the flavor of water dropwort.1.Using the method of SPME and GC-MS for extraction and separation of volatile compounds in water dropwort.The contents of volatile substances in leaves and petiole of water dropwort were 1628.58 μg/g and 818.68 μg/g after earth up softening cultivation,which were 46.41%and 66.75%lower than the control.There were 20 species and 16 species of volatile substances in the leaves and petioles of water celery,4 species and 8 species less than the control.The content of caryophyllene and γ-terpinene in the leaves of water dropwort was 0.54.The content of caryophyllene and γ-terpinene in petiole increased by 1.45 to 5.26,respectively.The proportion of fragrance in water dropwort increased after cultivation.2.Transcriptome sequencing was used to compare and classify the annotated Unigene with the functions in the database.A total of 5,258 and 6,035 sequences in the petiole and leaf of water dropwort were classified and annotated.Unigene was classified into 25 groups using COG database,and 22 and 23 groups were involved in petiole and leaf respectively,including biosynthesis,transport and catabolism of secondary metabolites related to terpenoids.Differentially expressed transcripts were classified according to the types of pathways in KEGG,and the number of differentially expressed transcripts in the synthesis pathway of terpenoids in petioles was 22.3.Fourteen family members of terpene synthase genes were identified from the transcriptome data of water dropwort by bioinformatics analysis.It was found that TPS1 and TPS5 were related to the synthesis of caryophyllene,and the expression of this gene was positively correlated with the content of caryophyllene.The function of TPS8 is related to the synthesis of γ-terpiene.The content of y-terpiene in the leaves and petioles of water dropwort was significantly decreased after the cultivation with soft soil,and the expression of this gene in the leaves and petioles of water dropwort was significantly reduced.