A reversible light- and genotype-dependent acquired thermotolerance response protects the potato plant from damage due to excessive temperature

A powerful acquired thermotolerance response in potato was demonstrated and characterised in detail, showing the time course required for tolerance, the reversibility of the process and requirement for light. Potato is particularly vulnerable to increased temperature, considered to be the most important uncontrollable factor affecting growth and yield of this globally significant crop. Here, we describe an acquired thermotolerance response in potato, whereby treatment at a mildly elevated temperature primes the plant for more severe heat stress. We define the time course for acquiring thermotolerance and demonstrate that light is essential for the process. In all four commercial tetraploid cultivars that were tested, acquisition of thermotolerance by priming was required for tolerance at elevated temperature. Accessions from several wild-type species and diploid genotypes did not require priming for heat tolerance under the test conditions employed, suggesting that useful variation for this trait exists. Physiological, transcriptomic and metabolomic approaches were employed to elucidate potential mechanisms that underpin the acquisition of heat tolerance. This analysis indicated a role for cell wall modification, auxin and ethylene signalling, and chromatin remodelling in acclimatory priming resulting in reduced metabolic perturbation and delayed stress responses in acclimated plants following transfer to 40 °C

Interactions between circadian rhythms, ROS and redox

Circadian rhythms are endogenous biological cycles with a period of about 24 h. In plants, circadian rhythms have a pervasive influence upon metabolism, physiology and development, yet we are still discovering how these rhythms interact with reactive oxygen species (ROS) generation and signalling. Recent work has identified circadian rhythms of ROS generation and ROS-scavenging enzymes, and there are also circadian rhythms of ROS-generating photosynthesis. Here, we summarise our current understanding of the relationship between the circadian system and ROS, and suggest roles for ROS in circadian signalling between organelles and the circadian regulation of guard cell function. There are circadian rhythms of peroxiredoxin oxidation state that occur in the absence of transcription and translation. It seems that there could be multiple levels of integration between ROS, redox and circadian regulation