Study On The Expression Of Iridoid Biosynthesis-related Genes In Tibetan Yin

Zang Yin Chen,germ of Chinese folk medicine,has been recognized as one of the eight most important Tibetan traditional medicine with good application prospect and value of exploitation and utilization.Zang Yin Chen is the most distinctive Tibetan medicine for the treatment of liver disease,febrile symptoms and blood of commonly used drugs,and clinically for the treatment of jaundice hepatitis,viral hepatitis,cholecystitis,etc.There are many different kinds of medicinal plants in Zang Yin Chen,approximately 20 species.It is mainly including some plants of genus Swertia,Halenia,Gentianopsis,Comastoma,Lomatogonium in the family Gentianaceae and genus Saxifraga in the family Saxifragaceae.Swertia mussotii is one of the original plants of Zang Yin Chen.The natural populations of Swertia mussotii,as one-year plants,are restricted to high altitudes(2,000 to 5,000 metres above sea level)in the Qinghai-Tibetan Plateau area in China,and mainly distributed in Tebet,Yunnan,northwest of Sichuan,southwest of Qinghai.In addition,the natural resource of Swertia mussotii yields less than before,while the demand of the crude drug market become higher.With the increasing demand for the species for medicinal use and the harvesting of flowering plants before fruit maturation,wild populations of Swertia mussotii are being exhausted because of over-collection.Reaearch on Swertia mussotii was focused on its pharmacological efficacy in recent years.Few reports are available on its molecular genetic basis.In this study,phenotypic traits,expression patterns of 7 genes encoding key enzymes in the secoiridoid pathway and contents of three different effective active compounds were analyzed,which can lay the foundation for the development and utilization of Swertia mussotii.The following is main results:(1)Three phenotypic traits of Swertia mussotii,one of the main original plants,were measured and analyzed,we found that plant height and the ratio of laminae length to width is extremely significant difference between different population.(2)Based on the analysis of transcriptome data,we identified 39 transcripts that could be classified into 24 enzyme categories associated with three metabolic pathways leading to secoiridoid biosynthesis.Based on the expression patterns of 7 genes encoding key enzymes in the secoiridoid pathway in different tissues,we found that there are significant differentiation of these genes in different tissues.The contents of bioactive compounds of the secoiridoid pathway in four tissues(root,leaf,stem,and flower)revealed that the expression profiles of the metabolic biosynthesis genes in different tissues did not show significant correlations in relation to the metabolite contents.The results revealed the complexity of gene expression and metabolite accumulation in the secoiridoid biosynthesis pathway.(3)The contents of three different effective active compounds(Gentiopicrin,Sweroside,Swertiamarin)of Swertia mussotii were determined,we found that the highest content of active compound was Gentiopicrin.In addition,ANOVA analysis of these active compounds showed that there were extremely significant difference among different Swertia mussotii.Furthermore,the contents of these active compounds are different in different places.In this study,Swertia mussotii was analyzed through the phenotypes,gene expression patterns and contents of three different effective active compounds,which enriched the phenotypes,genetic information and contents of effective active compounds of Swertia mussotii.Also,it will lay a foundation for the development and utilization of ethnic medicines.