Construction Of Phenotypic And Molecular Database Of Longan DUS Test

Plant variety distinctiveness,uniformity and stability(DUS)testing is an import technical support for plant variety rights protection,variety approval and variety registration.Longan(Dimocarpus longan Lour.)is not only an excellent tropical and sub-tropical fruit tree,but also have a long cultivation history and rich germplasm resources in China.Nowdays,the database of longan varieties of common knowledge is in blank,which makes it difficult to carry out the longan new plant variety protection,variety rights maintenance,the identification of varieties.In this article,the representative longan varieties of common knowledge were used as the researching object,and the basic work of collecting phenotypic data,making a classification of quantitative characteristics,taking the I.D.photos and screening of SSR molecular markers carried out and based on which,the phenotypic and molecular database of longan varieties of common knowledge had been constructed.The main research results are as follows:1.Based on the observation of 35 phenotypic characteristics of 63 longan varieties,the expression status were determined.Among the 35 phenotypic characteristics,5 quantitative characteristics,such as the main axis length of a compound leaf,petiole length,fruit size,pulp thickness and pericarp thickness,conformed to the normal distribution and the LSD auxiliary method was used for the classification of these quantitative characteristics.2.The analysis of phenotypic diversity of longan showed that there were 155 expression variation in 63 longan varieties,and 4.43 expression variations(range 1-8),2.84 effective expression variations(range 1.00-4.33)and 1.11 Shannon diversity information index(range 0-1.65)on average for each characteristic.Cluster analysis showed that the genetic similarity coefficient ranged between 0.62-0.91,and when the similarity coefficient was greater than 0.73,the 63 longan varieties could be divided into 7 groups.3.Analysis of genetic diversity of 63 longan varieties by using SSR markers showed that24 SSR markers produced 127 alleles in 63 varieties of longan,the valid variance was2.93(range is 1.50-4.20),Shannon’s information index of the 24 pairs of SSR markers ranged from 0.32 to 0.72,with an average of 0.58,which showed that the longan varieties used for research were rich in diversity.Cluster analysis showed that the genetic similarity coefficients ranged between 0.58-0.99,and when the similarity coefficient was greater than0.73,the 63 longan varieties could be divided into 6 groups.The candidate varieties with a genetic similarity of over 0.84 are assumed to be similar varieties.4.Mantel test showed that the correlation between the genetic similarity coefficients of phenotypic characteristics and SSR markers was significant,but the correlation coefficient was small(r=0.36).The above implies that SSR markers are unable to replace more phenotypic characteristics to be solely adopted to identify the distinctness of longan varieties,but the combination of phenotypic characteristics and SSR markers will effectively increase the accuracy of similar varieties.5.Technical specifications for taking 4 identity photos of longan varieties,such as plant,inflorescence,infructescence and single fruit were developed from 5 aspects,including shooting period,location,material preparation,picture background,and shooting technique requirements.These technical specifications provided a normative guidance for I.D.photos taking of longan variety DUS test.6.Make suggestions for modification of some trait types and observation methods in the "Guidelines for the conduct of tests for distinctness,uniformity and stability—Longan".