| Curcuma longa L.is a perennial herb of Zingiberaceae family.Turmeric essential oil is one of the main effective components of rhizome,which is composed of sesquiterpenes and has abundant biological activity.However,at present,the content of turmeric essential oil in plants is low,and the extraction conditions limit its yield,so it is difficult to meet the market demand.In this study,different turmeric germplasms were used as materials to optimize the extraction process of turmeric essential oil,compare their biological activities,and then isolate and identify some terpenoid synthases in turmeric,and regulate the gene expression.The main results of this study are as follows:1.The essential oil of Curcuma longa L.was extracted by different solvents and extraction processes.The results showed that the content of the main components obtained by Soxhlet extraction method was the highest at the ratio of 1:10 of material to liquid for 5 hours,reaching94.84%of the total components.The highest content of?-curcumin was 26.60%when the ratio of material to liquid was 1:15 for 6 h and 26.27%when the ratio of material to liquid was 1:20for 40 min by Soxhlet extraction.2.The highest extraction rate of essential oil from different turmeric germplasms was 3.52%.54 components were identified.Among them,sesquiterpene Eucalyptus oil,Cineole,?-curcumene,Ar-turmerone,Neocurdione and Curdione were the common components,and the content of Ar-turmerone was the highest,with an average of 28.26%.3.The free radical scavenging capacity of turmeric essential oil was determined by DPPH and ABTS methods.The IC50 values of turmeric germplasms showed that the antioxidant activities of G4,G3,H2 and J3 were stronger,and the IC50 values of G4 germplasms reached the lowest value of 6.47 mg·mL-1.Therefore,turmeric essential oil has moderate antioxidant capacity.4.The antimicrobial activity and antifungi activity showed that most turmeric essential oil exhibited significant bacteriostatic effect at low concentration(4.5 mg·mL-1);4.5 mg·mL-172mg·mL-1 turmeric essential oil exhibited significant inhibition of fungal growth,and the morphological changes of mycelia such as cytoplasmic ablation,mycelial entanglement,fragmentation and sporogenesis were observed.72 mg·mL-1 essential oil could inhibit 63.60%of mycelia growth at most.5.Four conserved fragments of turmeric terpenoid synthase genes C-HMGR,C-FPS,CSS1and CSS2 were obtained by homologous cloning.The length of C-HMGR gene nucleic acid sequence was 583 bp,encoding 189 amino acids,C-FPS fragment was 489 bp,encoding 162amino acids,CSS1 fragment was 438 bp,encoding 145 amino acids,CSS2 fragment 429 bp and152 amino acids.It is predicted that the four enzymes have terpenoid synthase catalytic domain and 34.13%70%similarity with their homologous genes.6.Different exogenous substances regulate the expression of four turmeric terpenoid synthases C-HMGR,C-FPS,CSS1 and CSS2 genes.The results showed that IAA,ABA,SA,GA3,CCC and chitosan could up-regulate the expression of four turmeric terpenoid synthase genes to varying degrees.Among them,the increase of CSS1 gene expression was not significant,CCC had no significant effect on the expression of C-HMGR and C-FPS genes.Even more,ABA and GA3 at 200?mol·L-1 down-regulated the expression of four genes by 16.61%-82.36%. |
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