Recent progress in selective breeding of maize (Zea mays L.) towards adaptation to temperate climate has allowed the production of inbred lines withstanding cold springs with temperatures below 8 °C or even close to 0 °C, indicating that despite its tropical origins maize is not inherently cold-sensitive. Here we studied the acclimatory response of three maize inbred lines of contrasting cold-sensitivity selected basing on multi-year routine field data. The field observations were confirmed in the growth chamber. Under controlled conditions the damage to the photosynthetic apparatus due to severe cold treatment was the least in the cold-tolerant line provided that it had been subjected to prior moderate chilling, i.e., acclimation. The cold-sensitive lines performed equally poorly with or without acclimation. To uncover the molecular basis of the attained cold-acclimatability we performed comparative transcriptome profiling of the response of the lines to the cold during acclimation phase by means of microarrays with a statistical and bioinformatic data analysis. The analyses indicated three mechanisms likely responsible for the cold-tolerance: acclimation-dependent modification of the photosynthetic apparatus, cell wall properties, and developmental processes. Those conclusions supported the observed acclimation of photosynthesis to severe cold at moderate chilling and were further confirmed by experimentally showing specific modification of cell wall properties and repression of selected miRNA species, general regulators of development, in the cold-tolerant line subjected to cold stress.

Cells are constantly confronted with endogenous and exogenous factors that affect their genomes. Eons of evolution have allowed the cellular mechanisms responsible for preserving the genome to adjust for achieving contradictory objectives: to maintain the genome unchanged and to acquire mutations that allow adaptation to environmental changes. One evolutionary mechanism that has been refined for survival is genetic variation. In this review, we describe the mechanisms responsible for two biological processes: genome maintenance and mutation tolerance involved in generations of genetic variations in mitotic cells of both Saccharomyces cerevisiae and Schizosaccharomyces pombe. These processes encompass mechanisms that ensure the fidelity of replication, DNA lesion sensing and DNA damage response pathways, as well as mechanisms that ensure precision in chromosome segregation during cell division. We discuss various factors that may influence genome stability, such as cellular ploidy, the phase of the cell cycle, transcriptional activity of a particular region of DNA, the proficiency of DNA quality control systems, the metabolic stage of the cell and its respiratory potential, and finally potential exposure to endogenous or environmental stress.