Glycyrrhizic Acid Content Variation In Issr And Sqs Gene-based Mechanisms

Glycyrrhizin content is one of the most important indexes to estimate the quality of medicinal licorice.One of the fundamental mesures to utilize medicinal licorice continuously is to develop cultivated licorice.It is of great importance to launch Species-selection of high quality.However,the researches on medicinal plant molecular seed breeding are still in weak situation because of the limit of the fine genes that can be applied to regulate the active component contents of medicinal plant directly.Thus to study the molecular mechanism of the variation of glycyrrhizin contents further in licorice is of practical significance as well as to other medicinal plant.Using ISSR,PCR-DNA sequencing,RT-PCR and Real-Time PCR methods,the paper studied the variance of genome and SQS gene amang 10 cultivated licorice individuals of different glycyrrhizin contents to elucidate the mechanism of the variation of glycyrrhizin contents.Main conclusions:(1)The genetic variations among different licorice individuals are concerned with the variations of glycyrrhizin contents among different licorice individuals.①There are genetic variation among the different licorice individuals in licorice colonia.②Based on the results of ISSR,most individuals of the high glycyrrhizin contents group gather as one branch,thus to elucidate that there are evident dependablities between genetic basis and high glycyrrhizin contents;and the individuals from the low glycyrrhizin contents group do not strictly gather as one branch,and the genetic distances are further among individuals of the low glycyrrhizin contents group(2)Gene mutation and the hybridization of SQS gene are concerned with the variations of glycyrrhizin contents in roots among different licorice individuals.①There are CA,AG and hybridization three genotypes of SQS gene in 10 different licorice individuals.Most individuals of the high glycyrrhizin contents group are CA and AG genotypes,while most individuals of the low glycyrrhizin contents group are the hybridization genotype.So to presume that the hybridization gene can be in coincidence with the accumulation as to the formation of low glycyrrhizin contents to some extent.②Gene mutation of some exons can result in the extreme variation of glycyrrhizin contents,and high glycyrrhizin contents result from the gene mutation as to No.98 bp from No.1 exon of SQS gene someway.(3)Gene mutation and the transform tendency of experssion level of SQS gene are concerned with the variations of glycyrrhizin contents among different licorice individuals.①The transform tendency of glycyrrhizin contents can affact in SQS gene experssion level.②SQS1 gene contributes more to the total SQS gene expressin level;the combination of the gene mutation of some SQS exons are likely to form the accumulation of glycyrrhizin contents in low level.(4)The transform tendency of SQS gene experssion level are concerned with the variations of glycyrrhizin contents among different location and months.SQS gene experssion or not in different location and months is associated with the accumulation of glycyrrhizin content:①SQS gene expression are in a high level in both leaves and roots of licorice in May;②while SQS gene expersses only in May in leaves and show no evidence of expression in August, September,October,November,Dcember and February;there are positive correlation among the SQS1 gene expression level and the accumulation of glycyrrhizin contents in May,August,September and October.In a word,there are genetic variances among cultivated licorice colonia,and the variances of SQS sequence and expression level both are concerned with the variation of glycyrrhizin contents.But the contribution ratio of the variances of SQS sequence and expression level to the variation of glycyrrhizin contents are required further studies.Innovations:(1)The variation of glycyrrhizin contents,especially the reduction of glycyrrhizin contents in cultivated licorice is the critical issure of the continuous development of medicinal licorice.Researches on Chinese crude drug as to the variation of glycyrrhizin contents have enforced from place of production, collection,cultivation skills etc.The paper discussed the molecular mechanism of the variation of glycyrrhizin contents and gained some conclusions.(2)In order to reveal the molecular mechanism of the variation of glycyrrhizin contents,the paper chose one of the functional genes,that is SQS gene to combined the polymorphism of functional gene order and the variance of functional gene expression to study molecular mechanism of the variation of glycyrrhizin contents and gained some conclusions.(3)So far,the researches on the association between the contents of main active components and gene of Chinese crude drug have been mainly on the variation of genome and single genes.The paper based on the ISSR variation of genome, has further studied the functional gene as to the formation of glycyrrhizin,and combined the variation of genome and functional gene to interprete the the variation of glycyrrhizin contents and gained some conclusions.The paper's results will be applied to be the bases of the seed selection and molecular seed breeding in licorice in the future.