Research Of Germplasm Resources And Genetic Diversity Of Snakegourd

Snakegourd (Trichosanthes kirilowii Maxim) is a perennial scramble liane belonging to the family Trichosanthes L. and it is an indigenous plant that was used as Chinese herb medicine for abortion about more than two thousand years. This study investigated the expression diversity of 12 varietier of Chinese snakegourd. Amplified fragment length polymorphism (AFLP) analysis was used to provide fingerprinting pattern for identification of 12 Chinese snakegourd cultivars. The fingerprinting pattern combined with the cell chromosome ploidy level analysis were used to evaluate the genetic diversity and relationship among Chinese snakegourd. Seed story protein were also analyzed used SDS-PAGE.The 12 plant materials have more or less morphological differences. The 12 genotypes were screened by 14 different AFLP primer combinations. A total of 645 loci were investigated of which 628 (97.36%) were polymorphic. The number of polymorphic loci detected by single primer combination for each variety was calculated and an average of 46.07 loci and 44.86 polymorphic marks were produced by per primer combination. Details on molecular weight of PCR product were collected and identified. Bands clearly visible in at least one cultivar were scored (1.for present, 0 for absent) and entered into a data matrix to create a qualitative data matrix. Pairwise similarities between accessions were calculated using Jaccard's coefficient and Nei and Li coefficient. The genetic distance was also calculated with the Jaccard's coefficient. Similarity based relationship between the genotypes were presented in the form of a dendrogram, according to the resulting similarity matrix (calculated with the Jaccard coefficient), developed by following unweighted pair group method with arithmetic mean algorithm (UPGMA) using SAHN clustering analysis of NTSYS-PC, version 2.1. The goodness-of-fit of the clustering was tested using the MXCOMP program, which directly compares the original similarity matrix and the cophenetic value matrix, as suggested by Rohlf. Nei's gene diversity and Shannon's Diversity Index were estimated using POPGENE software, version 1.32. To estimate the partitioning of AFLP genotypic variation between and within groups, analysis of molecular variance (AMOVA) was also performed, using Arlequin software. The result of this study showed pairwise distances calculated with the two indexes revealed exactly the same relationships between accessions, although similarity values were different. Genetic similarity values ranged from 0.0645 to 0.7270 (calculated with Jaccard's) and from 0.3252 to 0.8678 (calculated with Nei and Li's). Similarity relationships were described graphically by a dendrogram based on similarity matrix (calculated with Jaccard's) which clustered all accessions into two groups in which group 1(accession nos.1, 2, 3) are diploid and group 2 are octploid. Heterogeneity within a group was indicated by some divergent positions, such as no 2 within the group 1 and no 6 within the group 2. AMOVA result showed most of variation(99.67%) was found among groups, variation within groups was quite small(0.33%) comparatively.The relationship between snakegourd accessions based on the dendrogram, was not connect obviously with its geographical distribution. Among the accessions characterized, the minimum genetic similarity was observed between the accession no 11 and no 12 both of which come from jiaozuo henan province. Probably because of the minimum segregation due to close geographic distribution. The cluster distribution emphasises the existence of recognisable genetic similarity within varieties and genetic heterogeneity between them. As a herbal medicine, different accession have different pharmaceutical component. Among resources studied, plant material no. 8 from anyang henan provance famous for its root tuber and plant material no. 6 from changqing shangdong province namable for its fruit. In group 2, plant material no. 6 as the most valuable officinal material possessed one divergent position divided from all other officinal materials which indicated it has special genotype for great officinal value. Coincidently, we found plant material no. 10 from jiaozuo henan provance was the one has the smallest genetic distance with both two the most valuable accessions (genetic distance with no. 6 was 0.16 and with no. 8 was 0.14), which indicated this wild style has the most similar genotype to both two the most valuable accessions and may has higher officinal value.Snakegourd is a typical kind of dioecism, so it is a great material to study difference between male and female plant. In this study we try to find diversity between male and female snakegourd use. the most polymorphic molecular marker, but the result showed it is real difficult.SDS-PAGE analysis showed different snakegourd accession have seed protein differences, and the protein variation were connected closely to genetic variation.The following conclusions can be drawn from this study: (i) AFLP markers can be useful for distinguishing and identifying snakegourd cultivars, since all cultivars are uniquely characterised. The polymorphism observed among accessions was appropriate to differentiate cultivars. (ii) There is a high level of polymorphism and genetic variation within the studied accessions, (iii) Variation found among Diploids and Octploids were far more than variation within them, (iv) plant material no. 6 from changqing shangdong province as the most valuable officinal material possessed one divergent position divided from all other officinal materials which indicated it has special genotype for great officinal value, (v) Different snakegourd accession have different seed protein expression and the difference between seed protein was connect obviously with its genetic relationship.