Assessment of Genetic Variation within Mustard (Brassica juncea (L.) Czern & Coss) Germplasm in Sri Lanka using Fluorescent-based Amplified Fragment Length Polymorphic DNA Markers

摘要

Sri Lanka has above sixty mustard (B. juncea (L.) Czern & Coss) accessions of germplasm collection. Genetic diversity and the relationship among these accessions have yet to be studied completely. An investigation was conducted to determine the extentof diversity and relationships among mustard germplasm from Sri Lanka at the DNA level using Fluoresent-based Amplified Fragment Length Polymorphic marker technology (FAFLP). Genotypes comprising 44 mustard accessions from Sri Lanka, two Indian, a Bangladesh, a Chinese and one German mustard line were used for this study. Six spring-type canola (B. napus) varieties were selected as outliers. AFLP selective amplification was carried out with fluorescent-labelled selective amplification primers. Out of sixteen primer combinations, twelve FAFLP primer combinations generated a total of 589 bands, of which 418 (71%) were polymorphic. The genetic similarity coefficients within B. juncea accessions ranged 0.44-0.94. Using the similarity coefficient matrix ofBrassica genotypes based on FAFLP markers, a dendrogram was constructed. The dendrogram indicated that mustard accessions were grouped into eight main clusters. These findings led to conclude that B. juncea accessions from Sri Lanka show high levels ofgenetic variation amongst themselves and were genetically distant from Indian and German mustard lines. Presence of diverse genetic variation among B. juncea in Sri Lanka is mainly due to low level of exploitation. AFLP-based genetic distance interactioncan be used by breeders for cultivar development and fingerprinting of genotypes/cultivars. It further shows the importance in the characterization and identification of different accessions of wild relatives of mustard germplasm in Sri Lanka. The results of the present study could be used as a baseline of the relationships for future diversity assessment of mustards in Sri Lanka. This study demonstrated that FAFLP is a simple, fast and efficient technique and the great value of FAFLP markers in comparing genetic relationship and pattern of variation among the gene pool of mustard.