| dc.description.abstract | Methylation of the carboxyl group in PP2A and formation of the PP2A holoenzyme is a highly regulated process. The catalyzer of this process is Leucine carboxyl methyl transferase 1 (LCMT1). PP2A-C methylation is essential for the health of eukaryotic cells. In the knockdown lcmt1, only the unmethylated form of PP2A-C is present. It is expected for this knock-out lcmt1 to react poorly under stress conditions in comparison to WT which still holds the LCMT1 gene. The mutant lcmt1 grew in the same manner as WT in germination media. Further, we investigated how WT and lcmt1 reacted to nutrient deficiency and to the addition of H2O2, which induced oxidative stress. The importance of plants ability to adapt to the environment is important for the growth under conditions with deficiency of nutrients. The deficiency of nitrogen (N) and phosphorus (P) can have many negative consequences for crop production and can reduce yields. Visible traits of this deficiency are paler leaves from chlorosis or purple color from anthocyanin production. Potassium (K) has shown to be an important nutrient for the plant to grow under stressful conditions, where the tip of the leaves could be affected by chlorosis. This experiment showed that both WT and lcmt1 were affected by a lack of nitrogen and phosphorus. The leaves turned out paler/yellow and some had a purple color that could indicate anthocyanin production and chlorosis. Without P, the roots were shorter and without N the plant weight was lower than in media containing these nutrients. The deficiency of K did not seem to have any effects on the plants in this study and needs to be more researched. The oxidative stress experiment can show how important the methylation of PP2A-C in A. thaliana is under stress conditions. The results from treatment with H2O2 fluctuated. WT weighed more and had more elongated shoots with the addition of H2O2 compared to lcmt1. The mutant growth was impaired and showed the most inhibition. We also examined the expression of the genes involved in ROS scavenging like APXs and FSD1. HSP90 was investigated as it is involved in various stress responses. All genes were expressed at high levels in WT and lcmt1 in both the control and in the stressed treatment. WT induced with 0.5 mM H2O2 had higher expression of APXs, FSD1, and HSP90 in comparison to lcmt1 with the same treatment. These differences in gene expression in stress environments may show how important the PP2A-C methylation is for cell survival and health in these situations. | |
