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Analytical Study Of Sesame (Sesamum Indicum L.) Germplasm Seed, Biochemical And Molecular Markers

Posted on:2003-10-26Degree:DoctorType:Dissertation
Country:ChinaCandidate:L L F l o r e n t J - B . Q Full Text:PDF
GTID:1103360062985660Subject:Plant genetics and breeding
Abstract/Summary:PDF Full Text Request
This study was aimed (l)at analysing the sesame(Sesamum indicum L.) genetic resources using seed ( morphological and physiological Characteristics , biochemical markers such as seed protein and esterase electrophoresis and random amplified polymorphic DNA (RAPD) markers; and (2) at paving the way for uses of these markers/techniques including morphological traits for characterization of S. indicum L. accessions by pointing out their resolving power. To achieve this, experiments were carried in the field to evaluate the potential of 22 morphological traits in classifying sesame germplasm derived from sesame core collection of China and Benin (West Africa), under Hangzhou (China) growing conditions, using multivariate analysis. Seed morphometric parameters were also measured with the help of a PC software connected to a colour camera. Differences in ultra-dried seed storage potentialunder simulated Benin conditions (32"C) were estimated by quantifying thelevel of losses in seed viability and vigour. The genetic diversity and relationships among germplasm were determined using isozyme and RAPD data with numerical taxonomic techniques.From the study, it was found that the multivariate analysis of 22 morphological characteristics of the sesame sub-cluster collections allowed a clustering of the accessions in groups. In a few cases the recorded passport classification did not agree with the data collected. The Principal Components Analysis (PCA) for the interaction of the 22 traits used in characterizing the accessions showed that corolla hairiness, stem hairiness, density of capsule hair, 100-seed weight, ratio of seed length to seed width, days to flowering, ratio of capsule length tocapsule width, seed width, locules per capsule, seeds per capsule, capsule thickness and capsule width were the characteristics contributing most to the total variability and were determinant in the groups of accessions.From the results, differences between accessions in all seed parameters (seed area, length, diameter, circumference and roundness) were established. The area of seed varied greatly among accessions from 2.91 mm2 to 7.37 mm2; seed roundness varied from 1.16 to 1.45. Though seed size is highly influenced by environmental factors, it could be used for grouping accessions in broad classes.The examination of S. indicum germplasm accessions based on biochemical markers resulted in moderate differences between accessions. The results obtained by clusters did not form robust groups, which could be associated with geographic origin or seed coat colour. The zymogram for esterase extracted from seedlings had 13 bands out of which 9 were monomorphic. However, ENRAB 38-1-7 was distinct from all the other accessions. Since accessions differing in seed colour had identical esterase patterns, and vice versa, there is most Likely no correlation between esterase banding patterns and seed coat colour. Nevertheless, similarity in seedling-esterase patterns was correlated with geographic origin, accessions from China were grouped together, while those from Benin(West-Africa) formed a distinct group.In die study to evaluate genetic variation and relationships among sesame accessions using a PCR based strategy, a total of 53 fragments were produced by the 6 primers across all die materials. The number of fragment per primer varied from 4 to 14, widi an average of 8.83. Between 2 and 13 polymorphic bands were scored for each primer. Primers OPS29 and OPS38 gave die highest polymorphism. Out of 53 generated fragments, 48(90.6%) were polymorphic, indicating that there was considerable variation at DNA level inIVthe sesame germplasm investigated. Based on cluster analysis of RAPD data, the 15 accessions were classified in two major groups and one independent accession. Sesame accessions from different localities and those differing in seed coat colour were clustered together accordingly. The relationships depicted in the dendrogram may be supported by the heterogeneity occurred within individual accession. Overall, RA...
Keywords/Search Tags:Sesame (Sesamum indicum L.), Genetic diversity, Molecular markers, Seed Storage Potential, Germplasm Conservation, Ultra-dry seed technology, Seed Morphometrics, Cluster Analysis
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