The Essential Oil Chemotypes And ISSR Analysis Of Genetic Relationships Of Seven Varieties Of Thyme

In order to redress the misuse of the essential oil of thyme and provide references for thyme(Thymus L.)germplasm resources assessment, research on morphological characters, chemo-types and the genetic distances based on seven varieties of thyme cultivated in Shanghai was conducted.The results are as follows:According to the clustering analysis based on morphological characters, seven varieties of thyme were divided into two groups (Num equals 15), with the broaden leaf thyme (Thymus pulegioides), creeping thyme (Thymus serpyllum), golden thyme (Thymus citriodorus'Golden Queen') and silver thyme (Thymus vulgaris'Silver Posie') in one group, while German winter thyme (Thymus vulgaris'German'), French thyme (Thymus vulgaris'French') and English thyme (Thymus vulgaris'English') in the other.The main components of German thyme, French thyme and English thyme were all thymol, p-cymene,γ-terpinene, while that of the broaden leaf thyme were crvacrol, geraniol,γ-terpinen, that of the golden thyme were geraniol, citral and nerol, that of the silver thyme were thymol, and that of the creeping thyme were thymol and camphol. By clustering analysis (Num equals 15), seven varieties of thyme were divided into three groups corresponding to three chemo-types, namely thymol chemo-type, crvacrol chemo-type and geraniol chemo-type.The ISSR analysis of genetic relationships showed that the genetic distances between seven varieties of thyme ranged from 0.34 to 0.76. Clustering analysis indicated that seven varieties of thyme were divided into three groups with the similarity coefficient of 0.51, with German winter thyme, French thyme and English thyme, silver thyme and creeping thyme in one group, broaden leaf thyme in another and golden thyme in the third one. The results of correlation analysis showed that there was significant differences between the distances obtained by the methods based on the essential oil and ISSR analysis with an correlation coefficient of 0.66235(p<0.01), which indicated that the oil composition may be determined by series of genes on the genomes. The results will provide references for variety screening with super traits and oil composition improvement.