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Accueil du site → Doctorat → Allemagne → 2020 → Approaches to increase abiotic stress tolerance of potato plants (Solanum tuberosum)

Friedrich-Alexander-Universität Erlangen-Nürnberg (2020)

Approaches to increase abiotic stress tolerance of potato plants (Solanum tuberosum)

Lehretz Günter Gerhard

Titre : Approaches to increase abiotic stress tolerance of potato plants (Solanum tuberosum)

Auteur : Lehretz Günter Gerhard

Université de soutenance : Friedrich-Alexander-Universität Erlangen-Nürnberg

Grade : Doktorgrades Dr. rer. nat. 2020

Résumé partiel
The potato plant (Solanum tuberosum L.) is, due to its origin from cool mountainous regions, very sensitive to elevated temperatures. As temperatures are increasing due to global warming this has already led to tremendous yield losses. The aim of this work was to gain insights into the regulation of potato tuberization, especially under abiotic stresses. Moreover novel potato plants should be created which could withstand better the challenges of climate change, in particular heat and drought. In a first approach, transgenic potato plants were generated and characterized. Overexpression of the key tuberization regulator SP6A (a FLOWERING LOCUS T homologue) should provide insights into the control of source-sink balance. Therefore, under control of a strong promoter a codon-usage optimized version of SP6A (SP6Acop-HA) was used to achieve strong expression of the transcript. This resulted in extremely early tuberization but a concurrently impaired shoot growth indicating a strong impact of SP6A on the source-sink balance. These transgenic plants tuberized extremely early, but concurrently exhibited an impaired shoot growth. Additionally, transgenic tubers formed daughter tubers from stored tubers suggesting that the meristem identity of dormant tuber buds was altered. To further unravel the underlying mechanism a transcript profiling experiment was conducted with dormant tuber buds from both wild type and transgenic tubers. Comparative data analysis revealed a differential expression of several transcription factors controlling meristem identity, which supports the findings. Motivated by the severity of the phenotype of SP6Acop-HA overexpressing plants, an in silico search for putative small regulatory RNAs was performed. This led to the identification of a small RNA, named SES, repressing SP6A transcript accumulation in a sequence-specific manner, especially under elevated temperatures. The gained knowledge was used to design a construct that abolishes the activity of SES by providing an artificial target sequence, referred to as short tandem target mimicry (STTM), in excess. This construct was transformed in potato. The resulting plants did not show severe morphologic alterations but tuber formation was maintained even under continuous treatment with elevated temperatures.

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Page publiée le 28 décembre 2020