Characterization of heat acclimation and heat stress responses in Arabidopsis thaliana

Abstract

Heat stress poses a serious threat to plant survival and productivity, and has a direct influence on crop yield stability. Plants response to high temperature is tightly controlled by complex genetic networks. Plants can be acclimated through gradual pre-exposure to increasing temperatures and that in turn causes higher survival in subsequent and otherwise lethal heat stress conditions. To investigate the physiological and molecular processes underlying heat acclimation and recovery, we examined changes in Arabidopsis thaliana transcriptome throughout the acclimation and the subsequent heat shock treatment. Groups of differentially expressed genes and enriched biological pathways that constitute the heat transcriptional memory were identified. The function of flavonoids in plant heat stress were further explored experimentally. In addition, we observed altered stomata density and aperture responses in heat acclimated plants, and this might be partially controlled by AGAMOUS-LIKE16 (AGL16) transcription factor and its negative regulator microRNA824 (miR824). By utilizing an automated non-invasive phenotyping facility, we have developed a protocol to record plant growth and photosynthetic performance after heat stress in wild type Arabidopsis thaliana and mutant lines at daily intervals. Through an imaging-based analysis of plants growth, we confirmed impaired thermotolerance of hsp101 compared to wild type plants by a time-series growth, morphology and chlorophyll responses. This offers a novel experimental setup for thermotolerance screenings in Arabidopsis, with defined digital markers linking the function of selected genes in heat stress responses to phenotypic traits.