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Exploring the abiotic resistance traits of the local wild wheat relative, Thinopyrum distichum
Haridass, Kishalya. 2024. Assembly and annotation of the genome of the sea urchin Tripneustes gratilla. Unpublished masters dissertation. Stellenbosch : Stellenbosch University [online]. Available: https://scholar.sun.ac.za/handle/10019.1/131670 Thesis (MScAgric)--Stellenbosch University, 2024.
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Stellenbosch : Stellenbosch University
2025
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| access_status_str | Open Access |
| author | Haridass, Kishalya |
| author2 | Botes, Willem |
| author_browse | Botes, Willem Haridass, Kishalya |
| author_facet | Botes, Willem Haridass, Kishalya |
| author_sort | Haridass, Kishalya |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Haridass, Kishalya. 2024. Assembly and annotation of the genome of the sea urchin Tripneustes gratilla. Unpublished masters dissertation. Stellenbosch : Stellenbosch University [online].
Available: https://scholar.sun.ac.za/handle/10019.1/131670
Thesis (MScAgric)--Stellenbosch University, 2024. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/131670 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:44:34.165Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/131670 Exploring the abiotic resistance traits of the local wild wheat relative, Thinopyrum distichum Haridass, Kishalya Botes, Willem Le Maitre, Nicholas Stellenbosch University. Faculty of AgriSciences. Dept. of Genetics & Institute of Plant Biotechnology. Wheat -- Genetics Wheat -- Disease and pest resistance Triticum aestivum L. -- Climatic factors Thinopyrum distichum -- Speciation Soil salinization Salt-tolerant crops Wild wheats Wheat -- Effect of stress on UCTD Haridass, Kishalya. 2024. Assembly and annotation of the genome of the sea urchin Tripneustes gratilla. Unpublished masters dissertation. Stellenbosch : Stellenbosch University [online]. Available: https://scholar.sun.ac.za/handle/10019.1/131670 Thesis (MScAgric)--Stellenbosch University, 2024. ENGLISH ABSTRACT: The phenotypic and genetic diversity in plants is crucial for adapting to environmental changes, yet most breeding programs often prioritize producer and end-user preferences over genetic diversity, leading to the erosion of this resource. Evaluating both phenotypic and genetic diversity of germplasm is vital for maintaining healthy crops, especially with the growing need for improved cultivars amid rising global populations and climate change. Bread wheat (Triticum aestivum L. (AABBDD)) is derived from hybridisation with its crop wild relatives (CWRs): Triticum urartu (AA), Aegilops speltoides (BB), and Aegilops tauschii (DD). As one of the world's staple foods, with a forecast global harvest of around 800 million tonnes for 2024, improving wheat is critical for maintaining food security, as the global population is projected to reach 9.8 billion by 2050. Climate change exacerbates challenges in agriculture through increased greenhouse gas emissions resulting in rising temperatures, which lead to disruptions in precipitation patterns, and soil salinization. Halophytic plants, which can tolerate high salinity levels, through a combination of osmotic adjustment, ion homeostasis, and reactive oxygen species (ROS) management, survive in saline environments. While saline soil is not widespread in South Africa, its current distribution threatens the main wheat production areas. Thinopyrum distichum, a native CWR of wheat known for its salt tolerance ability, was collected from 42 coastal locations in the Western Cape province. Genetic diversity was assessed through PCR with 12 unique chloroplast markers, leading to the construction of a phylogenetic tree. Unexpectedly, the genetic relationships among the collected entries were unresolved (polytomy), raising questions about Th. distichum's historical indigenous status. A salinity tolerance trial was also conducted to assess phenotypic responses to increasing salt concentrations. Eleven morpho-physiological parameters were measured to identify individuals with greater salt tolerance. A Principal component analysis, and hierarchical cluster analysis highlighted a group of five genotypes that performed well under high salt stress, suggesting a level of diversity not captured by the markers used in the genetic diversity study section. These top performing genotypes showed reduced salt accumulation in comparison to wheat under salt stress, as confirmed by inductively coupled plasma atomic emission spectroscopy (ICP-AES) analysis. However, they accumulated more salt than wheat under non-stressed conditions. Further investigation into HKT7 gene expression, a key player in the salt-overly stressed pathway, which maintains ion homeostasis, revealed significant downregulation in the root tissue of salt exposed plants, under increasing durations of the salt stress. This, with the ICP-AES results confirmed Th. distichum as a salt-accumulating halophyte. This project was able to identify five potential crossing parents to be included in a wheat pre-breeding programme, for further investigation into their salt tolerance mechanisms and eventual transfer of tolerance to wheat. AFRIKAANSE OPSOMMING: Die beskikbare fenotipiese-en genetiese-diversiteit in plante speel ‘n belangrike rol om aan te pas by omgewingsverandering. Die meeste planteteeltprogramme prioritiseer egter dikwels die produsent- en eindgebruiker se voorkeure ten koste van genetiese-diversiteit wat lei tot die verlies van hierdie hulpbronne. Daarom is dit belangrik om beide die fenotipiese- en genetiese -diversiteit van kiemplasmabronne te evalueer om gesonde gewasse te handhaaf, veral met die groeiende behoefte aan verbeterde kultivars te midde van die toenemende wêreldbevolking en klimaatsverandering. Broodkoring (Triticum aestivum L. (AABBDD)) het ontstaan as gevolg van die natuurlike kruising van verskeie wilde-koringspesies: Triticum urartu (AA), Aegilops speltoides (BB), en Aegilops tauschii (DD). As ‘n belangrike stapelvoedsel, met ’n verwagte globale oes van ongeveer 800 miljoen ton vir 2024, is dit krities om koring te verbeter en sodoende voedselsekuriteit te handhaaf, aangesien die wêreldbevolking na verwagting teen 2050, 9.8 miljard sal bereik. Klimaatsverandering vererger huidige uitdagings in landbou aangesien verhoogde kweekhuisgasvrystelling tot aardverwarming lei. Hierdie veroorsaak op sy beurt ontwrigtings in reënvalpatrone en veroorsaak die verbrakking van grond deur die voorkoms van soute Halofitiese plante, wat hoë sout vlakke kan verdra, oorleef in sout-omgewings deur ’n kombinasie van osmotiese aanpassing, ioon-huisvesting, en die bestuur van reaktiewe suurstof spesies (ROS). Alhoewel brakgrond nie wydverspreid in Suid-Afrika is nie, bedreig die huidige verspreiding die belangrikste koringproduksie areas Thinopyrum distichum, ’n inheemse wilde-koringspesie wat bekend is vir sy soutverdraagsaamheid, is van 42 kusgebiede in die Wes-Kaap versamel. Genetiese-diversiteit is geëvalueer deur die konstruksie van ‘n filogenetiese-boom vanaf PKR-reaksies met 12 unieke chloroplastmerkers. Die genetiese verhoudings tussen die versamelde inskrywings kon nie verklaar word nie (politomie). Hierdie resultate was onverwags en het vrae gewerp oor Th. distichum se historiese inheemse status. ’n Soutverdraagsaamheidstoets is gedoen om die fenotipiese reaksies op toenemende sout konsentrasies te evalueer. Elf morfo-fisiologiese parameters is gemeet om inskrywings met groter sout verdraagsaamheid te identifiseer. ’n Hoofkomponent ontleding en hiërargiese kluster analise het ’n groep van vyf genotipes beklemtoon wat goed gevaar het onder hoë sout stres, wat dui op ’n vlak van diversiteit wat nie vasgelê is deur die merkers wat in die genetiese diversiteit studie gebruik is nie. Hierdie genotipes het goed presteer en onder sout stres ‘n verlaagde sout akkumulasie getoon in vergelyking met koring, soos bevestig deur induktief gekoppelde plasma-atoom-emissie spektroskopie (ICP- AES) -analise. Onder nie-stres kondisies het hulle egter meer sout as koring geakkumuleer. Die HKT7- geenuitdrukking, ’n sleutelrolspeler in die soutstres-padweg, wat ioon-huisvesting handhaaf, is verder ondersoek en is beduidend af gereguleer in die wortel weefsel van sout blootgestelde plante tydens toenemende periodes van sout stres. https://scholar.sun.ac.za Hierdie resultaat, asook die ICP-AES-resultate, het Th. distichum as ’n sout-akkumulerende halofiet bevestig. Hierdie projek het vyf potensiële kruisings ouers geïdentifiseer wat in koringteeltprogramme ingesluit moet word en die meganisme bevestig waardeur Th. distichum soutstress bestuur. Masters 2025-02-05T07:08:07Z 2025-02-05T07:08:07Z 2024-12 Thesis https://scholar.sun.ac.za/handle/10019.1/131670 en Stellenbosch University x, 113 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Wheat -- Genetics Wheat -- Disease and pest resistance Triticum aestivum L. -- Climatic factors Thinopyrum distichum -- Speciation Soil salinization Salt-tolerant crops Wild wheats Wheat -- Effect of stress on UCTD Haridass, Kishalya Exploring the abiotic resistance traits of the local wild wheat relative, Thinopyrum distichum |
| title | Exploring the abiotic resistance traits of the local wild wheat relative, Thinopyrum distichum |
| title_full | Exploring the abiotic resistance traits of the local wild wheat relative, Thinopyrum distichum |
| title_fullStr | Exploring the abiotic resistance traits of the local wild wheat relative, Thinopyrum distichum |
| title_full_unstemmed | Exploring the abiotic resistance traits of the local wild wheat relative, Thinopyrum distichum |
| title_short | Exploring the abiotic resistance traits of the local wild wheat relative, Thinopyrum distichum |
| title_sort | exploring the abiotic resistance traits of the local wild wheat relative thinopyrum distichum |
| topic | Wheat -- Genetics Wheat -- Disease and pest resistance Triticum aestivum L. -- Climatic factors Thinopyrum distichum -- Speciation Soil salinization Salt-tolerant crops Wild wheats Wheat -- Effect of stress on UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/131670 |
| work_keys_str_mv | AT haridasskishalya exploringtheabioticresistancetraitsofthelocalwildwheatrelativethinopyrumdistichum |