Browsing by Author "Sharma, R. K."

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    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.
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    Morpho-molecular genetic diversity and population structure analysis to enrich core collections in tea [Camellia sinensis (L.) O. Kuntze] germplasm of Sri Lanka and India
    (Genetic Resources and Crop Evolution, 2023) Kottawa-Arachchi, J. D.; Ranatunga, M. A. B.; Sharma, R. K.; Chaudhary, H. K.; Attanayake, R. N.; Amarakoon, A. M. T.; Gunasekare, M. T. K.; Sharma, B.; Kumar, N.; Sood, V. K.
    Despite tea [Camellia sinensis (L.) O. Kuntze] is one of the top non-alcoholic beverages consumed around the world; its genetic and phenotypic diversity is less understood compared to other plantation crops. The study’s aims were to undertake phenotypic and genotypic characterization of Sri Lankan and Indian tea germplasm and to identify diverse accessions to accelerate tea breeding programmes in both countries. A total of 171 tea accessions, comprising 94 Sri Lankan and 77 Indian accessions were used. All the accessions were subjected to phenotyping and genotyping using 28 polymorphic simple sequence repeat (SSR) markers. Based on 16 morphological characters, the first three principal components explained 57.61% and 58.43% of the total variability of Sri Lankan and Indian accessions, respectively. Young shoot pubescence, young shoot pigmentation, serration of leaf margin, and mature leaf colour contributed positively to the grouping of accessions. Based on Neighbor-joining analysis, all Sri Lankan accessions grouped in a single cluster, whereas Indian accessions grouped in two distinct clusters. The Gower’s distance method was the most appropriate than other methods for developing core subsets. Among 21 Sri Lankan core accessions selected, 11 accessions belong to introductions, five TRI-developed cultivars and five estate selections. Among 18 Indian core accessions selected, 11 belong to China types, two Assam types and five Indian recommended cultivars. The current study is the first study to compare tea germplasm of both countries and the results are useful for tea crop improvement programme, conservation and utilization of tea germplasm in India and Sri Lanka in the future.