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Identification of quantitative trait loci (QTLs) associated with agronomic traits in tea (Camellia sinensis) (L.) O. Kuntze
Dissertation (MSc)--University of Pretoria, 2019.
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| Language: | English |
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University of Pretoria
2026
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| _version_ | 1867613678679883776 |
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| access_status_str | Open Access |
| author2 | Apostolides, Zeno |
| author_browse | Apostolides, Zeno |
| author_facet | Apostolides, Zeno |
| collection | Thesis |
| dc_rights_str_mv | © 2024 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc)--University of Pretoria, 2019. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/107649 |
| institution | University of Pretoria (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:39:58.102Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/107649 Identification of quantitative trait loci (QTLs) associated with agronomic traits in tea (Camellia sinensis) (L.) O. Kuntze Apostolides, Zeno za@up.ac.za Koech, Robert Kipyegon UCTD Camelia sinensis Tea quality Drought tolerance DArTseq Linkage map Dissertation (MSc)--University of Pretoria, 2019. The identification of candidate genes associated with black tea quality and drought tolerance traits in tea (Camellia sinensis) plants remains complicated and time-consuming. This study aimed to identify molecular, physiological and biochemical characteristics associated with black tea quality and drought tolerance traits in two tea segregating populations for future marker-assisted selection breeding. The two tea segregating populations TRFK St. 504 and TRFK St. 524 were developed from a reciprocal cross of two heterozygous parental clones, TRFK 303/577 and GW Ejulu. Using Ultra-Performance Liquid Chromatography (UPLC), catechin fractions and theaflavin fractions was analysed in green and black tea, respectively, while caffeine content were analysed in both green and black tea. Black tea samples were further subjected to organoleptic evaluation by professional tea tasters to score liquor characters (colour, brightness, strength and briskness). The percent relative water content (%RWC) using Short-time Withering Assessment of Probability for Drought Tolerance (SWAPDT) method was used to distinguish between drought susceptible and drought-tolerant tea cultivars. A total of 16 phenotypic data from two segregating tea populations were used to identify the quantitative trait loci (QTLs) influencing tea biochemical, and drought stress traits based on a consensus genetic map constructed using the DArTseq platform. The map consisted of 15 linkage group and corresponded to chromosome haploid number of tea plant (2n = 2x = 30) and spanned 1 260.1 cM with a mean interval of 1.1 cM between markers. A total of 1 421 DArTseq markers derived from the linkage map identified 53 DArTseq markers to be linked to black tea quality and %RWC. The putative QTLs linked to black tea quality, and drought tolerance traits were submitted to BLAST and assigned functions using Gene Ontology (GO) terms and biosynthetic pathways in the tea genome, gene ontology database and Kyoto Encyclopedia of Genes and Genomes (KEGG). The approach of combining linkage mapping with association mapping allowed identification, and precise authentication of putative QTLs with an additional six more putative QTLs identified. The functional annotations of all the putative QTLs detected were involved in the metabolism of secondary metabolites associated with tea phenolic biomolecules and abiotic stress. The predictive ability of all machine learning models varied across the phenotypic traits. The putative QTLs + annotated proteins + KEGG pathways based prediction approach showed more robustness and usefulness in the prediction of phenotypes than the individual prediction based models. The Extreme Learning Machine (ELM) model had a better prediction ability for catechin, astringency, brightness, briskness and colour based on putative QTLs + annotated proteins + KEGG pathways approach. The percent variables of importance of putatively annotated proteins and KEGG pathways were associated with the phenotypic traits. FUNDING : The research work would not have been possible without the financial support, and I extend my thanks to James Finlay (Kenya) Ltd., George Williamson (Kenya) Ltd., Sotik Tea Company (Kenya) Ltd., Mcleod Russell (Uganda) Ltd., TRI of Kenya and Southern African Biochemistry and Informatics for Natural Products (SABINA), Technology and Human Resources for Industry Programme (THRIP), South Africa, National Research Foundation (NRF) of South Africa, and the University of Pretoria (South Africa) for the funds. Biochemistry, Genetics and Microbiology (BGM) MSc (Biochemistry) Restricted Faculty of Natural and Agricultural Sciences SDG-02: Zero Hunger 2026-01-28T09:03:27Z 2026-01-28T09:03:27Z 2019-04-24 2019-02-14 Dissertation * A2019 http://hdl.handle.net/2263/107649 N/A en © 2024 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | UCTD Camelia sinensis Tea quality Drought tolerance DArTseq Linkage map Identification of quantitative trait loci (QTLs) associated with agronomic traits in tea (Camellia sinensis) (L.) O. Kuntze |
| title | Identification of quantitative trait loci (QTLs) associated with agronomic traits in tea (Camellia sinensis) (L.) O. Kuntze |
| title_full | Identification of quantitative trait loci (QTLs) associated with agronomic traits in tea (Camellia sinensis) (L.) O. Kuntze |
| title_fullStr | Identification of quantitative trait loci (QTLs) associated with agronomic traits in tea (Camellia sinensis) (L.) O. Kuntze |
| title_full_unstemmed | Identification of quantitative trait loci (QTLs) associated with agronomic traits in tea (Camellia sinensis) (L.) O. Kuntze |
| title_short | Identification of quantitative trait loci (QTLs) associated with agronomic traits in tea (Camellia sinensis) (L.) O. Kuntze |
| title_sort | identification of quantitative trait loci qtls associated with agronomic traits in tea camellia sinensis l o kuntze |
| topic | UCTD Camelia sinensis Tea quality Drought tolerance DArTseq Linkage map |
| url | http://hdl.handle.net/2263/107649 |