Browsing by Author "Ranathunga, M. A. B."

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Assessment of selected biochemical parameters in a hybrid population of tea to predict the quality of processed tea
(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Abeysekara, R. M. U. N.; Kottawa-Arachchi, J. D.; Ranathunga, M. A. B.; Amarakoon, A. M. T.
Tea is made from the processed leaves of the mature tea plant, Camellia sinensis L. It is one of the most popular beverages in the world. Tea breeding programs constantly attempt to improve the yield and quality of tea by producing new cultivars. Biochemical and molecular markers are frequently used to assist the conventional tea breeding techniques. Chlorophyll a, b, total chlorophyll, carotenoids and total polyphenol content in tea leaves can be used as biochemical markers to predict the quality of processed tea. In this study, young shoots of 112 individuals from a hybrid progeny which was derived from TRI 2043 and TRI 3055 through controlled hybridization in Tea Research Institute of Sri Lanka were analyzed for chlorophyll a, b, total chlorophyll and carotenoid content. 102 individuals from the hybrid population were analyzed for total polyphenol content. Acetone (80%) extraction was used for the analysis of pigments and methanol (70%) extraction was used for the analysis of total polyphenol. Spectrophotometry (absorbance at 470 nm, 646 nm, 663 nm and 765 nm for chlorophyll a, b, carotenoids and total polyphenol respectively) was used with relevant standards for quantification. Statistical analysis (Minitab16 to determine frequency distributions using histograms and boxplots, SAS 9.1 to prepare dendrogram in cluster analysis) of the results had shown wide segregation of the measured parameters and some of the off springs had recorded higher values than the parents. According to the results, highest chlorophyll a content were recorded in accessions 134, 16 and 67 (3.25 mg/g, 3.10 mg/g and 2.92 mg/g respectively) and chlorophyll b in accessions 134, 16 and 67 were also higher than the others in the population (1.21 mg/g, 1.13 mg/g and 1.02 mg/g respectively). The total chlorophyll content in accessions 134, 16 and 67 were recorded as 4.46 mg/g, 4.23 mg/g and 3.95 mg/g respectively. Carotenoid content in accessions 77, 98 and 36 were higher than the others in the population (2.46 mg/g, 1.63 mg/g and 1.10 mg/g respectively). The highest total polyphenol content (33.13%) was recorded in parent TRI 3055. Total polyphenol contents in accessions 94, 72, 95, 92 and 102 were higher than the rest of the progeny (32.51%, 31.33%, 31.10%, 30.87% and 30.28%). Measured parameters of the hybrid population were subjected to cluster analysis. The resultant dendrogram clearly categorized the progeny into four clusters. Accessions with higher chlorophyll, carotenoid and polyphenol contents (accessions 150, 52, 35,134 and 16) could be candidates for the development of new cultivars with better quality tea
Molecular characterization of Sri Lankan tea [Camellia sinensis (L.) O. Kuntze] genotypes with diverse origins using SSR markers for future breeding programmes
(Faculty of Science, University of Kelaniya, Sri Lanka., 2021) Kottawa-Arachchi, J.D.; Ranathunga, M. A. B.; Sharma, R. K.; Amarakoon, A. M. T; Gunasekare, M. T. K.; Chaudhary, H. K.; Attanayake, R. N.
The tea plant [Camellia sinensis (L.) O. Kuntze] is one of the most popular non-alcoholic beverage crops worldwide. Tea germplasm is the most valuable and fundamental resource for breeding high yielding, climate resilient, and quality tea cultivars. Therefore, efforts were made to characterize the existing genetic diversity of Sri Lankan tea using simple sequence repeat (SSR) markers. A total of 91 tea accessions including exotic, estate selections, improved quality and diverse cultivars were selected for the diversity estimations. Eleven informative highly polymorphic SSR markers selected based on inferences of previous studies (EST, miRNA and traits associated SSR markers) were used in this study. Genetic relationships were analyzed by a neighbor-joining (NJ) tree constructed using DARwin software. Genetic structure analysis was performed by the Bayesian clustering model using STRUCTURE analysis and the optimum delta K was generated. Genetic diversity analysis grouped all the accessions into three major clusters. Further, structure analysis complemented the cluster analysis and revealed three genetic populations (China types with Korean origins, Assam types with ASM4/10 ancestral relationship and mixture of different origins) in the Sri Lankan tea germplasm. Newly recommended TRI5001, TRI5002, TRI5003 and TRI5004 cultivars have shown affinities with five Assam introductions and grouped together in the same cluster. Interestingly, five high yielding TRI developed cultivars (TRI2023, TRI2025, TRI3013, TRI3055 and TRI3073) having an ancestral relationship with the parent ASM4/10 were also grouped together. Likewise, seven accessions of Azerbaijan origin were remained together. The estate selections were scattered in the three clusters. The inferences of the current study provide molecular evidence for the genetic diversity and population structuring of the tea germpalsm and will help the selection of the potential parental group for the future cultivar development programme of Sri Lanka.