Biotic stress triggers an immune response in plants. The regulation of the immune response involves signaling pathways involving phytohormones, of which salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) are the most important. Monitoring of the spatiotemporal dynamics of the gene activation under a particular signaling pathway, and thus studying plant's stress response is made possible by using genetically encoded biosensors.
In the first part of the Master's thesis, we selected the most suitable biosensor of the SA signaling pathway in potato among four native promoters of genes TGA2_R, TGA2_PW, PR1b_R and PR1b_D.
For this purpose, the promoter sequences were fused with luciferase coding sequence. Promoter activity upon treatment with SA, JA and ET was tested after transient transformation of tobacco plants (Nicotiana benthamiana) by luciferase assay. Thus, we selected TGA2_R as the most SA-specific promoter for use in a biosensor.
In the second part of the thesis we optimized the first step of the method for determining promoter responsiveness in potato that is isolation of protoplasts. We isolated protoplasts from Rywal and Désirée potato cultivars according to three different protocols, and selected and optimized the most suitable one for protoplast transfection. We showed that 3–4 weeks old Rywal plants are optimal for isolation of potato protoplasts.
In the future, the selected promoter will be used for stable transformation of potato. Its use will lead us closer to understanding of potato plant response to stressors, which will aid in development of more robust cultivars.
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