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Induced mutation in potato to improve drought adaptation and productivity
Thesis (PhDAgric)--Stellenbosch University, 2026.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2026
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| _version_ | 1869484297375711232 |
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| access_status_str | Open Access |
| author | Mota, Maipato Margaret |
| author2 | Kempen, Estelle |
| author_browse | Kempen, Estelle Mota, Maipato Margaret |
| author_facet | Kempen, Estelle Mota, Maipato Margaret |
| author_sort | Mota, Maipato Margaret |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (PhDAgric)--Stellenbosch University, 2026. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/136139 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-07-01T04:12:39.332Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2026 |
| publishDateRange | 2026 |
| publishDateSort | 2026 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/136139 Induced mutation in potato to improve drought adaptation and productivity Mota, Maipato Margaret Kempen, Estelle Van der Vyver, Christell Stellenbosch University. Faculty of AgriSciences. Dept. of Agronomy. Potatoes -- Mutation breeding -- Africa, Southern Potatoes -- Effect of drought on Potatoes -- Drought tolerance Potatoes -- Genetics Greenhouse plants -- Water requirements UCTD Thesis (PhDAgric)--Stellenbosch University, 2026. Mota, M. M. 2026. Induced mutation in potato to improve drought adaptation and productivity. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/f7e9d300-877f-477e-92b8-110e121228e5 ENGLISH ABSTRACT: Potato is an important food security crop widely cultivated by smallholder farmers due to its extensive adaptation characteristics. However, potato production is often constrained by drought because of its shallow root system. Developing drought-tolerant varieties is therefore critical for mitigating the adverse effects of water scarcity. The overall aim of this study was to assess the response of the potato cultivars to drought stress and to develop drought-tolerant mutants. The specific objectives were: (i) to evaluate drought tolerance of four commercially grown potato varieties in Southern Africa under glasshouse conditions, (ii) to determine the optimal dosages of physical and chemical mutagens required for random mutation induction in potato through in vitro sensitivity tests, and (iii) to evaluate agronomic traits and adaptation responses of drought-tolerant potato mutants. Four potato cultivars (BP1, Up-to-date, Hertha, and Mondial) were evaluated under controlled glasshouse conditions to determine the effects of different water regimes on key agronomic traits. Significant variation in drought tolerance was observed among the varieties, highlighting the importance of understanding cultivar-specific responses to water stress. Notably, BP1 exhibited the highest tolerance to severe drought conditions among the cultivars. For mutation induction, BP1 and Up-to-date were selected for sensitivity testing with gamma rays and ethyl methanesulfonate (EMS). Nodal cuttings were used as explants to determine the optimal mutagen dosage or concentration. Regression analysis yielded LD50 values of 13.80 Gy for BP1 and 12.50 Gy for Up-to-date under gamma irradiation, and 8.40 mM EMS for BP1. The variation in lethal dosages and concentrations emphasises the need for variety-specific sensitivity assessments before mutagenic treatment. Bulk irradiation and chemical mutagenesis were carried out at the respective optimum dosages or concentrations, and explants were propagated in vitro up to M1V4 generation to dissolve chimeras and obtain stable mutations. Mutant plantlets at the M1V4 generation were then exposed to in vitro osmotic selection using polyethylene glycol (PEG) to facilitate preliminary screening for osmotic stress tolerance. The selected mutants were subsequently evaluated in pot trials, where they were subjected to two water regimes: 80% field water capacity (FWC) and 30% FWC, and their performance was compared with that of the parental line. From this screening, fifteen mutant lines with improved drought tolerance compared to parental lines were identified. A follow-up drought-tolerance evaluation was conducted to confirm these selections. This confirmation trial consisted of two sampling periods: a six-week assessment and a four-month assessment. The results showed that induced mutation through gamma irradiation and EMS significantly enhanced drought tolerance, although yields under drought were not higher than the control (Parent). Based on the overall findings, the following mutants are proposed as tolerant to water deficit: BP1 EMS 60, BP EMS 91, BP Gy 56, BP Gy 60, BP Gy 64, and BP1 72 Gy. These mutants should be further evaluated under field conditions in regions with limited water availability, as they maintain satisfactory growth, biomass production, and yield under both normal and drought conditions. AFRIKAANSE OPSOMMING: Aartappel is 'n belangrike voedselsekerheidsgewas wat wyd deur kleinboere verbou word as gevolg van sy uitgebreide aanpassingseienskappe. Aartappelproduksie word egter dikwels deur droogte beperk as gevolg van sy vlak wortelstelsel. Die ontwikkeling van droogtetolerante variëteite is dus van kritieke belang om die nadelige gevolge van waterskaarste te versag. Die oorhoofse doel van hierdie studie was om die reaksie van die aartappelkultivars op droogtestres te bepaal en droogtetolerante mutante te ontwikkel. Die spesifieke doelwitte was: (i) om die droogtetoleransie van vier kommersieel gekweekte aartappelvariëteite in Suider-Afrika onder kweekhuistoestande te evalueer, (ii) om die optimale dosisse fisiese en chemiese mutagene te bepaal wat benodig word vir ewekansige mutasie-induksie in aartappels deur middel van in vitro-sensitiwiteitstoetse, (iii) om agronomiese eienskappe en aanpassingsreaksies van droogtetolerante aartappelmutante te evalueer. Vier aartappelkultivars (BP1, Up-to-date, Hertha en Mondial) is onder beheerde glashuistoestande geëvalueer om die effekte van verskillende waterregimes op belangrike agronomiese eienskappe te bepaal. Beduidende variasie in droogtetoleransie is tussen die variëteite waargeneem, wat die belangrikheid van die begrip van kultivar-spesifieke reaksies op waterstres beklemtoon. Dit is opmerklik dat BP1 die hoogste toleransie vir ernstige droogtetoestande onder die kultivars getoon het. Vir mutasie-induksie is BP1 en Up-to-date gekies vir sensitiwiteitstoetsing met gammastrale en etielmetaansulfonaat (EMS). Nodale steggies is as eksplante gebruik om die optimale mutageendosis of konsentrasie te bepaal. Regressie-analise het LD50-waardes van 13.80 Gy vir BP1 en 12.50 Gy vir Up-to-date onder gammabestraling, en 8.40 mM EMS vir BP1 opgelewer. Die variasie in dodelike dosisse en konsentrasies beklemtoon die behoefte aan variëteitspesifieke sensitiwiteitsassesserings voor mutageniese behandeling. Grootmaatbestraling en chemiese mutagenese is uitgevoer teen die onderskeie optimale dosisse of konsentrasies, en eksplante is in vitro gekweek tot by die M1V4-generasie om chimeras op te los en stabiele mutasies te verkry. Mutante plantjies by die M1V4-generasie is toe blootgestel aan in vitro osmotiese seleksie met behulp van poliëtileenglikol (PEG) om voorlopige sifting vir osmotiese strestoleransie te vergemaklik. Die geselekteerde mutante is vervolgens in potproewe geëvalueer, waar hulle aan twee waterregimes onderwerp is: 80% veldwaterkapasiteit (FWC) en 30% FWC, en hul prestasie is vergelyk met dié van die ouerlyn. Uit hierdie sifting is vyftien mutantlyne met verbeterde droogtetoleransie in vergelyking met ouerlyne geïdentifiseer. 'n Opvolg droogtetoleransie-evaluering is uitgevoer om hierdie seleksies te bevestig. Hierdie bevestigingsproef het bestaan uit twee monsternemingsperiodes: 'n ses weke lange assessering en 'n vier maande lange assessering. Die resultate het getoon dat geïnduseerde mutasie deur gammabestraling en EMS droogtetoleransie aansienlik verbeter het. Gebaseer op die algehele bevindinge, word die volgende mutante voorgestel as verdraagsaam teenoor watertekort: BP1 EMS 60, BP EMS 91, BP Gy 56, BP Gy 60, BP Gy 64, en BP1 Gy 72 . Hierdie mutante word aanbeveel vir verbouing in streke met beperkte waterbeskikbaarheid, aangesien hulle bevredigende groei, biomassaproduksie en opbrengs onder beide normale en droogtetoestande handhaaf. Doctoral 2026-04-23T09:35:48Z 2026-04-23T09:35:48Z 2026-03 Thesis https://scholar.sun.ac.za/handle/10019.1/136139 en Stellenbosch University xxiv, 179 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Potatoes -- Mutation breeding -- Africa, Southern Potatoes -- Effect of drought on Potatoes -- Drought tolerance Potatoes -- Genetics Greenhouse plants -- Water requirements UCTD Mota, Maipato Margaret Induced mutation in potato to improve drought adaptation and productivity |
| title | Induced mutation in potato to improve drought adaptation and productivity |
| title_full | Induced mutation in potato to improve drought adaptation and productivity |
| title_fullStr | Induced mutation in potato to improve drought adaptation and productivity |
| title_full_unstemmed | Induced mutation in potato to improve drought adaptation and productivity |
| title_short | Induced mutation in potato to improve drought adaptation and productivity |
| title_sort | induced mutation in potato to improve drought adaptation and productivity |
| topic | Potatoes -- Mutation breeding -- Africa, Southern Potatoes -- Effect of drought on Potatoes -- Drought tolerance Potatoes -- Genetics Greenhouse plants -- Water requirements UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/136139 |
| work_keys_str_mv | AT motamaipatomargaret inducedmutationinpotatotoimprovedroughtadaptationandproductivity |