Methylation of PP2A - Effects of heat stress on gene expression and phenotype of Arabidopsis thaliana

The possible connection between protein phosphatase 2A (PP2A) and heat stress performance was explored in Arabidopsis thaliana by comparing wild type (WT) with a lcmt1 knockout mutant. In healthy organisms the enzyme leucine carboxyl methyl transferase 1 (LCMT1) is responsible for methylating PP2A. A lcmt1 mutant will not be able to methylate PP2A, and although the importance of methylation is poorly understood it has been shown to have a big effect under stress. The plants were grown in Petri dishes and in soil, exposed to various lengths of heat stress and any phenotype differences were observed. Certain differences in gene response were also observed by the use of real-time PCR. Results showed healthy growth, but with some differences in the mutant lcmt1 compared with WT under normal condition. However, under stress WT would outperform lcmt1 with the difference becoming more clear with increased stress. The expression levels of different genes were explored, and differences were found. Quantification cycle (Cq) and relative quantification (RQ) was examined, and especially values for heat shock protein 90-1 (HSP90-1) and iron-regulated transporter 1 (IRT1) stood out. Values were examined after 0 h, 1 h and 24 h of heat stress. The results were clearest after 24 h, where WT showed the strongest deviation from the control with strongly increased expression for HSP90-1 and strongly decreased expression for IRT1 compared with the mutant lcmt1