Green algal molecular responses to temperature stress

Global warming is a critical issue and has great impact on all living organisms, including algae. Generally, algae play significant roles in aquatic ecosystems and employ diverse strategies to survive under abiotic stress. For example, heat stress affects membrane fluidity, and algae, in response, can modify their membrane fatty acid composition to maintain homoeostasis. Moreover, they protect their proteins and enzymes using molecular chaperones or degrade denatured proteins in processes involving ubiquitin. In addition, algae regulate their carbohydrate concentrations and structures to utilise the energy of endogenous carbon sources efficiently and protect other molecules via accumulation of compatible solutes. Algae regulate the photosynthetic machinery to acclimatise to stress conditions. In fact, algae have a range of acclimation and repair strategies; and in the case where these strategies fail, programmed cell death (PCD) will be activated. Among algae, green algae have been massively studied due to their broad-range applications such as pharmaceutical, biofuel production and wastewater management, and being a suitable model to study plant and photosynthesis. Enhanced knowledge about the genes and proteins involved in the acclimation of green algae would enlighten our understanding of their acclimation pathways, and enable the genetic improvement of stress-tolerant strains. Thus, the mechanisms and pathways associated with green algal acclimation and repair strategies with an emphasis on temperature-related stress are highlighted in this review.