Title: Biodiversity Prospecting In Plant Genomes. A Comparative Study in Camellia sinensis using RAPDs, Catechins and Caffeine

摘要

Genetic diversity in Kenyan tea germplasm was analyzed using Random Amplified Polymorphic DNA (RAPDs) while the Biochemical diversity in the differential expression of Catechins and Caffeine was determined using High Performance Liquid Chromatography (HPLC). The Nei estimates of diversity for the RAPD fragments covering a total number of 143 loci gave a mean diversity index (H) of 0.49, while the Shannon Weaver index yielded a mean value of 0.75 for the catechins data and 0.74 for the caffeine data. Analysis of the similarity of the RAPD fragments using average Cluster Linkage Analysis yielded two taxonomic groups; the Assam and China varieties while analysis of the combined catechin attributes using the Principal Component Analysis resolved the tea into three taxomic groups; China, Assam and Cambod varieties. Interestingly, PCA analysis of the caffeine data with a Shannon Weaver index similar to the combined catechin attributes yielded a very low level of resolution compared to either the RAPDs Catechins. These results show that a combination of biochemical attributes is more robust and therefore a better estimator of genetic differentiation compared to the use of individual attributes. This finding is important because catechins exist in many structural forms, and are relatively stable and easy to quantify and their relative amounts could, therefore, be used to measure prevailing levels of diversity in germplasm collections. The results also show that the high diversity indices seen in the caffeine data do not necessarily reflect a high level of genetic differentiation. It is evident that the high indices could be reflecting mainly high intra-varietal differences. These results, therefore, have an important bearing in policies regarding germplasm enrichment and conservation.