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NAC transcription factors in sugarcane and their functional role in drought tolerance
Thesis (MSc)--Stellenbosch University, 2026.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2026
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| _version_ | 1867613933161938944 |
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| access_status_str | Open Access |
| author | Meyer, Werner |
| author2 | Van der Vyver, Christell |
| author_browse | Meyer, Werner Van der Vyver, Christell |
| author_facet | Van der Vyver, Christell Meyer, Werner |
| author_sort | Meyer, Werner |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2026. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/136240 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:44:01Z |
| 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:10019.1/136240 NAC transcription factors in sugarcane and their functional role in drought tolerance Meyer, Werner Van der Vyver, Christell Stellenbosch University. Faculty of Sciences. Dept. of Botany and Zoology. Thesis (MSc)--Stellenbosch University, 2026. Meyer, W. 2026. NAC transcription factors in sugarcane and their functional role in drought tolerance. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/7e463759-b556-45fa-bb0f-d5b176f8559a Sugarcane (Saccharum spp. hybrid) is a major global sugar crop with high biomass productivity but marked sensitivity to water deficit. It is cultivated in many countries, including South Africa, where drought severity and frequency are expected to increase in the coming decades. This underscores the need for genetic engineering strategies to enhance drought tolerance and ensure the long-term sustainability of sugarcane production. Conventional breeding has had limited success due to the complex, polygenic nature of abiotic stress responses, highlighting the importance of identifying single regulatory elements capable of modulating multiple stress response pathways. NAC (No apical meristem [NAM], Arabidopsis transcription activation factor [ATAF], Cup-shaped cotyledon [CUC]) transcription factors (TFs) are promising candidates, as they influence plant development, stress signalling, and cell division. In cowpea (Vigna unguiculata) and Arabidopsis, the constitutive overexpression of the VuNAC1 TF improved growth, photosynthetic activity, and tolerance to dehydration, salinity, and metal stress through the enhanced accumulation of osmoprotective metabolites. In this study, two NAC TFs were overexpressed in transgenic plants and assessed under in vitro osmotic and cold stress, as well as in water-deficit pot trials. Although VuNAC1 was successfully introduced into Saccharum spp. hybrid cv. NCo310 sugarcane via microprojectile bombardment, its expression was undetectable in the surviving transgenic plantlet, leaving the role of VuNAC1 in sugarcane development and stress tolerance unresolved. Interest in the mechanisms by which VuNAC1 improved transgenics’ performance motivated the search for functionally similar NAC genes in sugarcane. Database and phylogenetic analyses identified ShNAC23 as a putative VuNAC1 orthologue implicated in drought and cold responses. Quantitative real-time PCR confirmed that endogenous ShNAC23 is significantly upregulated under osmotic and moderate cold stress. ShNAC23 was introduced into tobacco via Agrobacterium-mediated transformation, and physiological and biochemical parameters were evaluated under water-deficit conditions. Transgenic plants displayed enhanced early growth vigour, but drought responses did not mirror the protective effects documented for VuNAC1. Relative water content remained lower than in wild-type plants, and no improvements were observed in chlorophyll content, PSII efficiency, or stomatal conductance. Oxidative stress markers were unchanged or elevated, and only one transgenic line showed increased proline accumulation and superoxide dismutase (SOD) activity, suggesting limited activation of osmotic and antioxidant defences. Germination assays further indicated that ShNAC23 did not enhance early seedling performance under osmotic or cold stress. Future work involving tissue-specific expression, inducible promoter systems, and transcriptomic analyses should clarify the regulatory role of ShNAC23 to determine if its transgenic expression can provide a harmonised enhancement of growth and drought tolerance. Masters 2026-04-29T07:38:31Z 2026-04-29T07:38:31Z 2026-03 Thesis https://scholar.sun.ac.za/handle/10019.1/136240 en Stellenbosch University 138 pages application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Meyer, Werner NAC transcription factors in sugarcane and their functional role in drought tolerance |
| title | NAC transcription factors in sugarcane and their functional role in drought tolerance |
| title_full | NAC transcription factors in sugarcane and their functional role in drought tolerance |
| title_fullStr | NAC transcription factors in sugarcane and their functional role in drought tolerance |
| title_full_unstemmed | NAC transcription factors in sugarcane and their functional role in drought tolerance |
| title_short | NAC transcription factors in sugarcane and their functional role in drought tolerance |
| title_sort | nac transcription factors in sugarcane and their functional role in drought tolerance |
| url | https://scholar.sun.ac.za/handle/10019.1/136240 |
| work_keys_str_mv | AT meyerwerner nactranscriptionfactorsinsugarcaneandtheirfunctionalroleindroughttolerance |